6th Grade Science Chapter 9 Forces

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.

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.

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.

Oppositely magnetized poles attract each other because they have opposite magnetic fields. The north pole of one magnet is attracted to the south pole of another magnet, and vice versa. This is due to the magnetic force between the poles, which pulls them together.

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.

Magnetic force is indeed the force that occurs between two magnetic poles. It can be an attractive or repulsive force depending on the nature of the poles (like poles repel each other, while opposite poles attract each other). This force is a fundamental aspect of magnetism and is described by the laws of electromagnetism.

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.

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.

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.

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.

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.

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.

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.

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".

Similar charges actually repel each other, not attract. This is because similar charges have the same polarity, either positive or negative. According to Coulomb's Law, like charges repel each other due to the electrostatic force between them. Therefore, the correct answer is False.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.