Forces and Motion Unit Test Review

During the annual school sports day, Sarah and her friends, Lily and James, are competing in a thrilling race. Can you guess which unit they might use to measure their speed?

• miles

• m/s

• yard

• grams

Answer explanation

The correct unit for speed is m/s (meters per second), as it measures distance over time. Miles and yards are units of distance, while grams measure mass, making m/s the only appropriate choice for speed.

Sophia and Ava are on an exciting adventure, watching a rocket blast off into the sky! The rocket's engines roar as they push down on the ground with immense force. In a thrilling twist, the ground pushes the rocket upwards with an equal force, but in the opposite direction. Which law of physics is behind this spectacular event?

• The Universal Law of Gravity

• Newton's 1st Law of Motion

• Newton's 2nd Law of Motion

• Newton's 3rd Law of Motion

Answer explanation

Newton's 3rd Law of Motion states that for every action, there is an equal and opposite reaction. The rocket pushes down on the ground, and the ground pushes the rocket upwards with an equal force, illustrating this law.

Emma and Zoe are racing shopping carts at the grocery store. Which of the following is not true about the unbalanced forces acting on their carts?

• They cause a change in motion of an object.

• They will cause acceleration of an object.

• They will cause the velocity of an object to change.

• They will not cause acceleration of an object.

Answer explanation

The statement 'They will not cause acceleration of an object' is not true because unbalanced forces do cause acceleration, as per Newton's second law. All other statements correctly describe the effects of unbalanced forces.

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Imagine Lilly and Rowan are in a friendly competition to push a box across the floor. Which type of force will keep the box from speeding up?

• gravity

• balanced forces

• unbalanced forces

• frictional forces

Answer explanation

Balanced forces occur when two forces acting on an object are equal in size and opposite in direction, resulting in no net force and no acceleration. Therefore, they do not cause the box to accelerate.

Isla and Samuel are racing with carts! Can you help Isla figure out the force needed to push her cart? It's equal to _________ * acceleration.

• mass

• speed

• distance

Answer explanation

Isla pushes a cart with a force that is equal to mass times acceleration, as stated in Newton's second law of motion (F = ma). Therefore, the correct answer is 'mass'.

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Scarlett and Henry were having a friendly debate about physics. Scarlett placed a coin on a table and asked Henry, "Which of these options BEST applies Newton’s First Law of Motion to this scenario?"

• The coin started off in motion until an unbalanced force caused it to stop

• The coin started off in motion until a balanced force caused it to stop

• The coin started off at rest until an unbalanced force caused it to move

• The coin started off at rest until a balanced force caused it to move

Answer explanation

According to Newton's First Law, an object at rest stays at rest until acted upon by an unbalanced force. The coin remains at rest until a force, like a push, causes it to move.

Lily and Ethan are having a friendly tug-of-war with a box, each pushing from opposite sides with equal force. Which statement about their forces is not true?

• The forces are balanced.

• The net force is zero.

• The forces are equal and opposite.

• The forces will cause a change in the object's motion.

Answer explanation

The statement "The forces will cause a change in the object's motion" is not true because Lily and Ethan are applying equal and opposite forces, resulting in balanced forces and a net force of zero, which does not change the motion.

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Zoe is on a mission to move a mysterious, heavy box to the left. To succeed in her quest, the unknown force must have a strength -

• of more than 25 N.

• of more than 125 N.

• of less than 25 N.

• of exactly 25 N.

Answer explanation

To move the box to the left, the applied force must overcome any opposing forces. If the box requires less than 25 N to move, then a force of less than 25 N is sufficient to achieve movement to the left.

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At the annual science fair, Sophia and Grace dazzled the audience with their project on which legendary scientist's discoveries revolutionized our understanding of forces and motion?

• Albert Einstein

• Galileo

• Isaac Newton

• Mrs. Telle

Answer explanation

Isaac Newton's work laid the foundation for classical mechanics, explaining the laws of motion and universal gravitation, which are crucial for understanding forces and motion in our world.

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Nora is on a thrilling adventure in her physics class, exploring the wonders of motion. She discovers that velocity is speed -

• with a given mass.

• with a given acceleration.

• in a controlled lab.

• in a specific direction.

Answer explanation

Velocity is defined as speed in a specific direction, distinguishing it from speed, which is a scalar quantity. Therefore, the correct answer is 'in a specific direction.'