# 6th Grade Science Chapter 9 Forces

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Quizzes Created: 5 | Total Attempts: 5,070
Questions: 59 | Attempts: 2,832  Settings  • 1.

### A force is simply a ________ or ________.

Explanation
A force is simply a push or pull. This means that a force can either push an object away from something or pull an object towards something. These two actions, push and pull, are the basic ways in which forces can act on objects.

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• 2.

### A force is described by its ________ (size) and ________.

Explanation
A force is described by its strength, which refers to the magnitude or intensity of the force, and its direction, which indicates the path or orientation in which the force acts. The strength determines how powerful the force is, while the direction specifies where the force is applied. Both strength and direction are essential in fully understanding and characterizing a force.

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• 3.

### Anytime you see a change in an object's motion, you can be sure that the change in motion was created by a ________.

Explanation
Anytime you see a change in an object's motion, it can be attributed to a force. Force is a physical quantity that can cause an object to accelerate or decelerate, change direction, or change its shape. It is the interaction between two objects that results in a change in motion. Without the presence of a force, an object would continue to move in a straight line at a constant speed, as stated in Newton's first law of motion. Therefore, the correct answer is force.

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• 4.

### Scientists express force by using a unit called the:

• A.

Joule (J)

• B.

Newton (N)

• C.

Kg/m

• D.

Pound (lb)

B. Newton (N)
Explanation
The correct answer is newton (N). Scientists express force using the unit newton (N) because it is the standard unit of force in the International System of Units (SI). The newton is defined as the force required to accelerate a one-kilogram mass by one meter per second squared. It is named after Sir Isaac Newton, who made significant contributions to the field of physics and formulated the laws of motion. The newton is widely used in various scientific fields, including mechanics, engineering, and physics, to quantify and measure forces.

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• 5.

### All of these are examples of contact forces EXCEPT:

• A.

Friction

• B.

Buoyant force

• C.

Gravity

• D.

Tension

C. Gravity
Explanation
This question is asking for an example of a contact force that is NOT included in the given options. The options provided are friction, buoyant force, gravity, and tension. Friction is a contact force that opposes the motion of objects in contact, buoyant force is the upward force exerted by a fluid on an object immersed in it, tension is the force transmitted through a string, rope, or cable when it is pulled tight, and gravity is the force of attraction between two objects with mass. Out of these options, gravity is the only non-contact force, as it acts at a distance between objects with mass.

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• 6.

### When the buoyant force pushing up on an object is equal to the force of gravity pushing down on the object, the object will sink.

• A.

True

• B.

False

B. False
Explanation
When the buoyant force pushing up on an object is equal to the force of gravity pushing down on the object, the object will not sink. This is because the buoyant force is the upward force exerted by a fluid on an object immersed in it, and it is equal to the weight of the fluid displaced by the object. If the buoyant force is equal to the force of gravity, the object will experience a net force of zero and will neither sink nor float, but rather remain suspended in the fluid.

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• 7.

### If the force of gravity on the object is less than the buoyant force pushing up on the object, the object will sink.

• A.

True

• B.

False

B. False
Explanation
If the force of gravity on the object is less than the buoyant force pushing up on the object, it means that the buoyant force is greater than the force of gravity. According to Archimedes' principle, an object will float when the buoyant force is greater than or equal to the force of gravity. Therefore, if the force of gravity is less than the buoyant force, the object will not sink but rather float. Hence, the statement "the object will sink" is incorrect, making the answer False.

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• 8.

### Friction happens only between objects that are touching.

• A.

True

• B.

False

A. True
Explanation
Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It occurs only when there is contact between two objects. Therefore, the statement that friction happens only between objects that are touching is correct.

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• 9.

### The amount of friction between two surfaces depends on two main factors. One is how ________ the surfaces are that are in contact. The other factor is the ________ pushing the surfaces together.

rough
force
Explanation
The amount of friction between two surfaces depends on two main factors. One is how rough the surfaces are that are in contact. Rough surfaces have more irregularities and bumps, which create more friction when they come into contact with each other. The other factor is the force pushing the surfaces together. The greater the force, the more the surfaces are pressed against each other, increasing the friction between them.

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• 10.

### When a force is applied to an object but doesn't cause the object to move, ________ friction occurs. This is a potential friction.

static
Explanation
Static friction occurs when a force is applied to an object but doesn't cause the object to move. This type of friction prevents the object from sliding or moving when a force is applied to it. It is called "static" because the object remains in a static or stationary position due to the frictional force acting on it. Static friction is a potential friction because it is present when an object is at rest and can be overcome by applying a greater force.

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• 11.

### What are the two types of kinetic friction?

• A.

Static and potential

• B.

Tension and sliding

• C.

Rolling and distant

• D.

Sliding and rolling

D. Sliding and rolling
Explanation
The correct answer is sliding and rolling. Kinetic friction refers to the force that opposes the relative motion between two surfaces in contact. Sliding friction occurs when two surfaces slide against each other, while rolling friction occurs when an object rolls over a surface. These two types of friction are distinct from each other and have different characteristics.

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• 12.

### Anything that has wheels uses ________ kinetic friction.

rolling
Explanation
When an object with wheels moves, it experiences rolling kinetic friction. Rolling friction occurs when the wheels of an object roll over a surface, causing the object to move. Unlike sliding friction, where two surfaces slide against each other, rolling friction is generally lower because the wheels rotate smoothly, reducing the amount of friction between the object and the surface. This type of friction is commonly observed in vehicles, such as cars, bicycles, and skateboards, where the wheels roll on the ground to facilitate movement.

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• 13.

### Friction can be reduced by using/applying lubricants such as motor oil, grease, or wax.

• A.

True

• B.

False

A. True
Explanation
Using lubricants such as motor oil, grease, or wax can reduce friction because these substances create a layer between the surfaces in contact, allowing them to slide more easily over each other. This layer of lubricant reduces the roughness and stickiness of the surfaces, resulting in less resistance and friction. Therefore, it is true that friction can be reduced by using/applying lubricants.

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• 14.

### Friction can be reduced by switching from rolling friction (wheels) to sliding friction.

• A.

True

• B.

False

B. False
Explanation
The statement is false because switching from rolling friction to sliding friction would actually increase friction, not reduce it. Rolling friction is generally lower than sliding friction because it involves the rolling of an object over a surface, while sliding friction involves the rubbing or sliding of an object against a surface. Therefore, switching from rolling friction to sliding friction would result in an increase in friction.

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• 15.

### ________ are substances that are applied to surfaces to reduce the friction between the surfaces.

Lubricants, lubricants
Explanation
Lubricants are substances that are applied to surfaces to reduce the friction between them. By creating a thin layer between the surfaces, lubricants help to minimize the contact and rubbing between them, thus reducing wear and tear. Lubricants can be in the form of liquids, oils, greases, or even solid materials, depending on the specific application. They are commonly used in various industries, such as automotive, manufacturing, and engineering, to ensure smooth operation and prolong the lifespan of machinery and equipment.

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• 16.

### One way to increase friction is to make surfaces smoother.

• A.

True

• B.

False

B. False
Explanation
The statement is false because making surfaces smoother actually reduces friction. Smoother surfaces have less roughness and fewer irregularities, which results in less resistance and friction between the surfaces.

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• 17.

### ________ is a force of attraction between objects that is due to their masses.

Gravity, gravity
Explanation
Gravity is a fundamental force of attraction between objects that is directly proportional to their masses. It is responsible for the phenomenon of gravitational pull, which causes objects to be drawn towards each other. The strength of gravity depends on the mass of the objects involved, with larger masses resulting in stronger gravitational forces. This force plays a crucial role in the behavior of celestial bodies, such as planets, stars, and galaxies, as well as on a smaller scale, influencing the motion of objects on Earth.

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• 18.

### The Law of Universal Gravitation states that all objects in the universe attract each other through gravitational force.

• A.

True

• B.

False

A. True
Explanation
The Law of Universal Gravitation, formulated by Sir Isaac Newton, states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. This gravitational force is always present and acts between all objects, regardless of their size or distance from each other. Therefore, it can be concluded that the statement "all objects in the universe attract each other through gravitational force" is true.

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• 19.

### The size of the gravitational force depends on the ___________ of the objects and the ____________________ the objects.

• A.

Distance, size of

• B.

Masses, distance between

• C.

Weight, distance between

• D.

Distance, pull of

B. Masses, distance between
Explanation
The size of the gravitational force depends on the masses of the objects and the distance between them. The greater the mass of the objects, the stronger the gravitational force between them. Similarly, the closer the objects are to each other, the stronger the gravitational force. Therefore, the size of the gravitational force is determined by the masses of the objects and the distance between them.

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• 20.

### Gravitational force increases as mass increases.

• A.

True

• B.

False

A. True
Explanation
Gravitational force is directly proportional to the mass of an object. This means that as the mass of an object increases, the gravitational force it exerts also increases. This relationship is described by Newton's law of universal gravitation, which states that the force of gravity between two objects is directly proportional to the product of their masses. Therefore, the statement that gravitational force increases as mass increases is true.

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• 21.

### The gravitational force is large between objects that have small masses.

• A.

True

• B.

False

B. False
Explanation
The explanation for the given answer, which is False, is that the gravitational force is actually larger between objects that have larger masses. According to Newton's law of universal gravitation, the gravitational force between two objects is directly proportional to the product of their masses. Therefore, if the masses of the objects are small, the gravitational force between them will also be small.

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• 22.

### The gravitational force is large when the mass of one or both objects is large.

• A.

True

• B.

False

A. True
Explanation
The gravitational force between two objects is directly proportional to the mass of both objects. This means that as the mass of one or both objects increases, the gravitational force between them also increases. Therefore, the statement that the gravitational force is large when the mass of one or both objects is large is true.

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• 23.

### Gravitational force increases as distance increases.

• A.

True

• B.

False

B. False
Explanation
The statement is incorrect. Gravitational force actually decreases as distance increases. This is explained by Newton's law of universal gravitation, which states that the force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. As the distance between two objects increases, the gravitational force between them decreases.

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• 24.

### The gravitational force is strong when the distance between two objects is small.

• A.

True

• B.

False

A. True
Explanation
The explanation for the given correct answer is that according to Newton's law of universal gravitation, the force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. This means that as the distance between two objects decreases, the gravitational force between them becomes stronger. Therefore, the statement that the gravitational force is strong when the distance between two objects is small is true.

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• 25.

### If the distance between two objects increases, the gravitational force pulling them together increases.

• A.

True

• B.

False

B. False
Explanation
The statement is false because according to Newton's law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them. This means that as the distance between two objects increases, the gravitational force pulling them together decreases.

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• 26.

### An object's weight cannot change with gravitational force.

• A.

True

• B.

False

B. False
Explanation
The statement "An object's weight cannot change with gravitational force" is false. Weight is the force exerted on an object due to gravity, and it can change depending on the strength of the gravitational force. For example, an object would weigh less on the moon compared to the Earth due to the moon's weaker gravitational pull. Therefore, the weight of an object is directly influenced by the gravitational force acting upon it.

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• 27.

### An object's mass doesn't change.

• A.

True

• B.

False

A. True
Explanation
The statement "An object's mass doesn't change" is true. Mass is a fundamental property of an object that remains constant regardless of its location or the forces acting on it. Mass is different from weight, which is the force exerted on an object due to gravity and can vary depending on the gravitational field strength. Mass is an intrinsic property of an object and is not affected by external factors.

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• 28.

### ________ is the rate at which velocity changes.

Acceleration, acceleration
Explanation
Acceleration is the rate at which velocity changes. When an object's velocity changes, it means that it is either speeding up or slowing down. Acceleration measures how quickly this change in velocity occurs. It is a vector quantity, meaning it has both magnitude (the amount of change in velocity) and direction. Acceleration can be positive (when velocity increases) or negative (when velocity decreases). In this case, the answer is "acceleration" because it is the rate at which velocity changes.

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• 29.

### The acceleration due to the Earth's gravity (_____) is the same for all objects near Earth's surface.

• A.

9.8 m/s²

• B.

10.4 m/s²

• C.

6.8 m/s²

• D.

9.2 m/s²

A. 9.8 m/s²
Explanation
The acceleration due to the Earth's gravity is the same for all objects near Earth's surface because gravity is a constant force that acts on all objects equally. This acceleration, represented by the value 9.8 m/s², is known as the acceleration due to gravity or the gravitational constant. It means that every second, an object near Earth's surface will experience a change in velocity of 9.8 meters per second in the downward direction due to gravity.

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• 30.

### The two factors that affect the acceleration due to gravity are ________ and ________.

• A.

Size, distance

• B.

Distance, mass

• C.

Weight, speed

• D.

Mass, force

D. Mass, force
Explanation
The two factors that affect the acceleration due to gravity are mass and force. Mass refers to the amount of matter an object contains, and force refers to the push or pull acting on an object. In the case of gravity, the force of gravity is proportional to the mass of an object. Therefore, the greater the mass of an object, the greater the force of gravity acting on it, resulting in a greater acceleration due to gravity.

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• 31.

### For every second that an object falls, the object's downward velocity increases by 9.8 m/s².

• A.

True

• B.

False

A. True
Explanation
The statement is true because according to the laws of physics, when an object falls, it experiences a constant acceleration due to gravity. This acceleration is approximately 9.8 m/s², which means that the object's velocity increases by 9.8 meters per second every second it falls. Therefore, the statement accurately describes the relationship between the object's falling time and its increasing downward velocity.

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• 32.

### If you drop a piece of notebook paper and a coin from the same height at the same time, they will reach the ground at the same time.

• A.

True

• B.

False

B. False
Explanation
The statement is false because the piece of notebook paper and the coin will not reach the ground at the same time. This is because the piece of notebook paper has a larger surface area compared to the coin, causing it to experience more air resistance. The air resistance slows down the descent of the paper, while the coin, being denser and having a smaller surface area, is less affected by air resistance and falls faster. Therefore, the coin will reach the ground before the piece of notebook paper.

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• 33.

### ________ is the force that opposes the motion of objects through the air.

Air resistance, air resistance
Explanation
Air resistance is the force that opposes the motion of objects through the air. It is caused by the collision of air molecules with the surface of the moving object. As the object moves through the air, the air resistance increases, making it harder for the object to continue its motion. This force depends on factors such as the speed and shape of the object. Objects with larger surface areas or higher speeds experience greater air resistance, while objects with streamlined shapes experience less air resistance.

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• 34.

### If you drop a piece of notebook paper and a coin from the same height at the same time, air resistance has a greater affect on the piece of paper than on the coin.

• A.

True

• B.

False

A. True
Explanation
Air resistance affects objects differently based on their size, shape, and surface area. In this case, the piece of notebook paper has a larger surface area compared to the coin, which means it experiences more air resistance. The air resistance slows down the paper more than the coin, causing it to fall at a slower rate. Therefore, the statement that air resistance has a greater affect on the piece of paper than on the coin is true.

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• 35.

### The upward force of air resistance continues to increase until it is equal to the downward force of gravity. At this point, the net force is 0 N and the object stops accelerating.

• A.

True

• B.

False

A. True
Explanation
As an object falls, the force of gravity pulls it downwards. At the same time, the force of air resistance acts in the opposite direction, increasing as the object gains speed. Eventually, the force of air resistance becomes equal to the force of gravity, resulting in a net force of 0 N. When the net force is 0 N, the object stops accelerating and reaches a terminal velocity, where the upward force of air resistance balances out the downward force of gravity. Therefore, the statement is true.

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• 36.

### The upward force of air resistance continues to increase until it is equal to the downward force of gravity. At this point, the net force is 0 N and the object stops accelerating. The object then falls at a constant velocity, called the ________ velocity.

Terminal, terminal
Explanation
When an object is falling, the upward force of air resistance initially increases until it becomes equal to the downward force of gravity. This balance of forces causes the net force on the object to be zero, resulting in the object no longer accelerating. At this point, the object falls at a constant velocity, which is referred to as the terminal velocity. Therefore, the correct answer is "Terminal, terminal."

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• 37.

### ________ motion is the curved path that an object follows when it is thrown or propelled near the surface of Earth.

Projectile, projectile
Explanation
Projectile motion is the curved path that an object follows when it is thrown or propelled near the surface of the Earth. This type of motion occurs when an object moves horizontally while also experiencing vertical acceleration due to gravity. The object follows a parabolic trajectory, with its path being influenced by both its initial velocity and the force of gravity. This type of motion is commonly observed in activities such as throwing a ball or shooting a projectile.

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• 38.

### Because objects in projectile motion accelerate downward, you usually have to aim below your target if you want to hit it with a thrown or propelled object.

• A.

True

• B.

False

B. False
Explanation
In projectile motion, objects do not accelerate downward. Instead, they experience a constant acceleration due to gravity, which acts vertically downward. This means that the horizontal motion of the object is not affected by gravity. As a result, if you want to hit a target with a thrown or propelled object, you do not need to aim below it. Therefore, the statement is false.

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• 39.

### The ________ force is the combination of all of the forces acting on an object.

Net, net
Explanation
The term "net, net" refers to the net force, which is the combination of all the forces acting on an object. It represents the overall force that is responsible for the object's motion or lack thereof. By summing up all the individual forces, we can determine the net force and understand how it affects the object's behavior.

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• 40.

### Forces in the same direction oppose each other. Forces in different directions reinforce each other.

• A.

True

• B.

False

B. False
Explanation
Forces in the same direction reinforce each other, while forces in different directions oppose each other. This is because when forces act in the same direction, their magnitudes add up, resulting in a stronger overall force. On the other hand, when forces act in different directions, their magnitudes subtract from each other, leading to a weaker overall force. Therefore, the statement in the question is incorrect.

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• 41.

### When the forces on an object produce a net force of 0 N, the forces are ________.

Balanced, balanced
Explanation
When the forces on an object produce a net force of 0 N, it means that the forces are equal in magnitude and opposite in direction. This is known as a balanced force. A balanced force does not cause any change in the object's motion, resulting in a state of equilibrium. In this case, the forces are balanced both in terms of magnitude and direction, leading to a net force of 0 N.

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• 42.

### Force = ________ x Acceleration

Mass, mass
Explanation
The equation for force is given by multiplying mass by acceleration. In this case, the blank should be filled with "mass" to indicate that force is directly proportional to mass. Therefore, the correct answer is "mass, mass".

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• 43.

### ________ is done when a force causes an object to move in the direction of the force.

Work, work
Explanation
Work is done when a force causes an object to move in the direction of the force. In this case, the word "work" is repeated twice, suggesting that it is the correct answer. The repetition emphasizes the concept being described, reinforcing the idea that work is indeed done when a force causes an object to move in the direction of the force.

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• 44.

### Work = Force x ________

Distance, distance
Explanation
The equation for work is given by multiplying the force applied to an object by the distance over which the force is applied. Therefore, the correct answer is "distance" as it represents the distance traveled or covered while applying a force. This equation helps quantify the amount of work done on an object.

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• 45.

### ________ is the rate at which energy is transferred.

Power, power
Explanation
Power is the rate at which energy is transferred. It is the measure of how quickly work is done or how quickly energy is converted or transferred from one form to another. Power is calculated by dividing the amount of work done or energy transferred by the time it takes to do the work or transfer the energy. Therefore, the correct answer is power.

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• 46.

### Power = ________ / time

• A.

Work

• B.

Force

• C.

Distance

• D.

Mass

A. Work
Explanation
The correct answer is "Work" because power is defined as the rate at which work is done or energy is transferred. Work is the amount of energy transferred by a force acting through a distance, and power is the rate at which this work is done. Therefore, power is equal to work divided by time.

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• 47.

### Which of these equations is NOT correct?

• A.

Force = Mass x Acceleration (F = MA)

• B.

Power = Force x Work (P = FW)

• C.

Work = Force x Distance (W = F x d)

• D.

Power = Work / time (P = W/t)

B. Power = Force x Work (P = FW)
Explanation
The equation Power = Force x Work (P = FW) is not correct. The correct equation for power is Power = Work / time (P = W/t).

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• 48.

### Electrical force and magnetic force are both ________ forces.

Distant, distant
Explanation
The correct answer is "long-range, long-range". Electrical force and magnetic force are both long-range forces because they can act on objects that are far away from each other. Unlike contact forces, such as friction or tension, which require objects to be in direct contact, electrical and magnetic forces can act over large distances. These forces follow an inverse square law, meaning that their strength decreases as the distance between the objects increases. Therefore, they can be considered as long-range forces.

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• 49.

### Magnetic force is based on positive and negative charges.

• A.

True

• B.

False

B. False
Explanation
The statement is incorrect. Magnetic force is not based on positive and negative charges. It is a force that is exerted by magnets and magnetic fields. Magnetic force is a result of the motion of charged particles, such as electrons, in a magnetic field. It is not directly related to positive and negative charges.

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• 50.

### Magnetic force is the force between two magnetic poles.

• A.

True

• B.

False

A. True
Explanation
The statement is true because magnetic force is indeed the force that exists between two magnetic poles. When two magnets are brought close to each other, they either attract or repel each other depending on the orientation of their poles. This force of attraction or repulsion is known as magnetic force. It is responsible for various phenomena such as the interaction between magnets and magnetic materials, as well as the functioning of devices like electric motors and generators.

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