7th Grade Physics Practice Test

When a book rests on a table and remains at rest, it means that there is no net force acting on it. This implies that the forces acting on the book are balanced, meaning that the forces are equal in magnitude and opposite in direction. Therefore, the correct answer is "balanced".

The correct answer is "state of motion" because it accurately describes an object's velocity or speed with a direction. It indicates that the object is moving and provides information about its direction of movement.

Mass is the correct answer because it refers to the amount of matter in an object. It is a fundamental property of an object and is measured in kilograms. Mass is different from weight, which is the force exerted on an object due to gravity. Inertia refers to an object's resistance to changes in motion, while velocity is the speed and direction of an object's motion.

A Newton is a unit of measurement for force. It is named after Sir Isaac Newton, a physicist who formulated the laws of motion. The Newton is defined as the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared. It is commonly used in physics and engineering to quantify the amount of force exerted on an object.

Friction is the force that resists the movement of one surface against another. It occurs when two objects are in contact and sliding or trying to slide against each other. Friction acts in the opposite direction of the applied force, making it more difficult for the objects to move. It depends on factors such as the nature of the surfaces, the force pressing them together, and the roughness of the surfaces. Friction plays a crucial role in everyday life, as it allows us to walk, drive, and hold objects without them slipping out of our hands.

Acceleration is the correct answer because it represents the rate at which an object changes its velocity. It is a vector quantity that includes both the magnitude and direction of the change in velocity. When an object speeds up, slows down, or changes direction, it is experiencing acceleration. Therefore, acceleration is the most appropriate term to describe the rate of change in velocity.

When the leg of the chair breaks, the support that was keeping the student in a balanced position is lost. As a result, gravity becomes the dominant force acting on the student. Since gravity is a greater force than any other force acting on the student, the student will accelerate towards the floor.

Gravity is the correct answer because it is the force of attraction that exists between two objects. It is the force that pulls objects towards each other and is responsible for the phenomenon of weight. Gravity is a fundamental force in the universe and plays a crucial role in the motion of celestial bodies, as well as everyday objects on Earth. It is the reason why objects fall to the ground when dropped and why planets orbit around the sun.

Speed is defined as the distance covered within a certain unit of time. It is a scalar quantity that measures how fast an object is moving, regardless of its direction. Speed does not take into account the direction of motion or any changes in direction, only the rate at which an object is moving. Therefore, speed is the correct answer in this case.

Weight is the correct answer because it refers to the amount of force exerted on an object due to gravity. Weight is a measure of the gravitational force acting on an object, and it is directly proportional to the mass of the object. The more massive an object is, the greater its weight will be. Weight is commonly measured in units of force, such as pounds or newtons.

Kinetic energy is the energy possessed by an object due to its motion. It is dependent on both the object's mass and its velocity. When an object is in motion, it has the potential to do work and transfer energy. This energy is known as kinetic energy. It can be calculated using the formula 1/2 mv^2, where m is the mass of the object and v is its velocity. Therefore, the correct answer is kinetic.

Centripetal force is the type of force that keeps objects moving in a circle or arc. It is directed towards the center of the circle and is responsible for continuously changing the direction of the object's velocity, while the object itself moves along the circular path. This force is required to counterbalance the natural tendency of objects to move in a straight line, allowing them to maintain their circular motion.

Inertia is the tendency of an object to resist changes in its motion. When the roller coaster stops quickly, the students' bodies want to keep moving forward due to their inertia. This means that even though the coaster has stopped, the students' bodies continue moving forward until another force, such as the seatbelt or the restraint system, stops them. Therefore, the correct answer is that the students' bodies keep moving forward.

The given correct answer is "inertia." Inertia is the tendency of an object to resist any changes in its state of motion. If an object is at rest, it will remain at rest, and if it is in motion, it will continue moving in a straight line unless acted upon by an external force. Inertia is a fundamental property of matter and is related to an object's mass.

According to the First Law of Motion, for a rocket to lift off, the thrust produced by its engines must be larger than the combined forces of gravity and the rocket's weight. This larger thrust creates a net positive force in the upward direction, allowing the rocket to overcome Earth's gravitational pull and ascend into space.

Velocity is the correct answer because it refers to the rate at which an object is traveling in a certain direction. It is a vector quantity that includes both the speed and direction of an object's motion. Acceleration refers to the rate of change of velocity, while speed refers to the rate at which an object is moving without considering its direction. Mass, on the other hand, is a measure of the amount of matter in an object and is not directly related to the rate of its motion.

Newtonʼs first law is the law of inertia. The marble that rolls into the dominos in my Rube Goldberg has inertia because it will keep rolling until acted on by a force, such as hitting the domino! The domino also has inertia, and it will keep staying still until acted on by a force, such as being hit by the marble.

Momentum is defined as the product of an object's mass and its velocity. It is a vector quantity, meaning it has both magnitude and direction. The momentum of an object can be calculated by multiplying its mass by its velocity. This concept is important in understanding the motion and interactions of objects.

The explanation for the given correct answer, Newton's Third Law, is that it states that for every action, there is an equal and opposite reaction. In the case of the Wheeler Dealer bumper cars, when one car collides with another, the action of the collision creates a reaction force that pushes the second car in the opposite direction with an equal amount of force. This demonstrates Newton's Third Law of motion.

In this demonstration, multiple simple machines are used. The inclined plane is used for the ball to roll down the ramp, reducing the effort needed. The wheel and axle is used in both the ball and the toy car, allowing them to roll smoothly. Lastly, the pulley is used to lift the cup tied to the rope, making it easier to drop to the ground. Therefore, all of the above options are correct answers.

In the context of the provided options, a rocket taking off and accelerating upward is the best illustration of this law. The force (thrust) exerted by the rocket engines propels the rocket upward, and the acceleration depends on the mass of the rocket. This scenario demonstrates the direct relationship between force, mass, and acceleration as described by the second law of motion.

The scenario described in the question is an example of inertia. Inertia is the tendency of an object to resist changes in its state of motion. When the student shakes the ketchup bottle while it is upside down, the ketchup initially does not move because it resists changes in its motion due to inertia. However, when the bottle is smacked, a force is applied to overcome the inertia, causing the ketchup to move. The ketchup continues to move until the bottle is turned upright because of its inertia to resist changes in motion.

Newtonʼs third law talks about how forces come in pairs, and when you push an object, it pushes back. The ball pushes on the floor when it hits, and the floor pushes back, one of the reasons why the ball comes back up.

The given answer demonstrates the Second Law of Motion. According to Newton's second law, the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. In this situation, the smaller player initially moves faster because he has less mass, which means he experiences a greater acceleration for the same force applied. Similarly, the larger player will move the dummy further because he has more mass, meaning he will experience a smaller acceleration for the same force applied.

When all the forces acting upon an object balance each other, the object will be in a state of equilibrium. In this state, there is no net force acting on the object, causing it to remain either at rest or in a state of constant motion with a constant velocity. This means that the object's acceleration is zero, and it experiences a balanced state where the forces cancel each other out.