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Forces and Motion Practice Tests

These Grade 8 Science practice tests cover pushes and pulls, newtons, net force, balanced and unbalanced forces, gravity, friction, mass, weight, speed, acceleration, motion graphs, free-body diagrams, and introductory Newton laws.

Skills covered

  • Identifying force, net force, balanced forces, and unbalanced forces
  • Distinguishing mass from weight and contact from noncontact forces
  • Calculating and interpreting speed, acceleration, and simple F = ma relationships
  • Reading distance-time graphs and force diagrams
  • Applying inertia and Newton laws to everyday motion and safety situations

How to use these practice tests

Draw or imagine the force arrows first. Add opposite forces carefully to find net force, then decide whether the object accelerates. For numerical questions, write the relationship, substitute the known values, and check the units.

For more Grade 8 Science practice, return to the Grade 8 Science category.

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Grade 8 Forces and Motion Practice Tests

Practice Grade 8 Science questions about forces, net force, balanced forces, friction, gravity, mass, weight, speed, acceleration, graphs, and Newton laws.

Choose the best answer for each question. Analyze force diagrams, motion data, graphs, mass, acceleration, friction, gravity, and Newton law relationships.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

What does Newtons First Law describe?

Please select an answer first.

Correct answer: A

The correct answer is An object keeps its state of motion unless an unbalanced external force acts on it..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

The First Law is the law of inertia and describes resistance to changes in motion.

2. QuestionMultiple choice

What is inertia?

Please select an answer first.

Correct answer: B

The correct answer is The tendency of an object to resist changes in its motion.

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

Inertia depends on mass: objects with greater mass generally resist changes more strongly.

3. QuestionMultiple choice

Which equation represents Newtons Second Law?

Please select an answer first.

Correct answer: C

The correct answer is F = ma.

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

Newton Second Law relates net force, mass, and acceleration with F = ma.

4. QuestionMultiple choice

If the same force acts on a larger mass, what happens to acceleration?

Please select an answer first.

Correct answer: D

The correct answer is The acceleration decreases..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

For a fixed force, acceleration equals force divided by mass, so greater mass gives smaller acceleration.

5. QuestionMultiple choice

What does Newtons Third Law state?

Please select an answer first.

Correct answer: A

The correct answer is For every force, there is an equal and opposite force..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

Forces occur in interaction pairs that act on different objects and have equal size and opposite direction.

6. QuestionMultiple choice

Which is an action-reaction pair?

Please select an answer first.

Correct answer: B

The correct answer is A swimmer pushes water backward, and the water pushes the swimmer forward..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

The swimmer and water exert equal opposite forces on each other.

7. QuestionMultiple choice

Why does a rocket move upward when gases are pushed downward?

Please select an answer first.

Correct answer: C

The correct answer is The gases exert a downward force and the rocket experiences an equal opposite upward force..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

The rocket and gases form an action-reaction pair described by Newtons Third Law.

8. QuestionMultiple choice

How does a seat belt demonstrate Newtons First Law?

Please select an answer first.

Correct answer: D

The correct answer is It provides a force that changes a passengers forward motion when the car stops..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

The seat belt prevents the passenger from continuing forward due to inertia.

9. QuestionMultiple choice

Why can a person push backward on the ground and move forward while walking?

Please select an answer first.

Correct answer: A

The correct answer is The ground pushes forward on the persons foot in response to the backward push..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

Friction and the action-reaction pair between foot and ground help produce forward motion.

10. QuestionMultiple choice

What is the relationship between mass and inertia?

Please select an answer first.

Correct answer: B

The correct answer is More mass generally means more resistance to a change in motion..

  1. Identify the motion information: Find the direction, distance, time, speed, acceleration, mass, or force described in the situation or data.
  2. Compare forces: Determine whether forces are balanced, calculate the net force when possible, and connect the result to motion.
  3. Apply the model: Use Newton law relationships, diagrams, graphs, or observations to explain the change in motion.

Mass is a measure of inertia, so a more massive object is harder to accelerate or stop.

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