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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

How can a rough surface affect friction?

Please select an answer first.

Correct answer: A

The correct answer is It can increase friction and make sliding more difficult..

  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.

Rough surfaces can create more interlocking and resistive interaction between surfaces.

2. QuestionMultiple choice

Why would an object weigh less on the Moon than on Earth?

Please select an answer first.

Correct answer: B

The correct answer is The Moon exerts a weaker gravitational force on the same mass..

  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.

Weight depends on gravitational field strength, while the objects mass stays the same.

3. QuestionMultiple choice

What does a free-body diagram show?

Please select an answer first.

Correct answer: C

The correct answer is The forces acting on one object with arrows showing direction and relative size..

  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.

A free-body diagram isolates an object and represents the external forces acting on it.

4. QuestionMultiple choice

What condition describes equilibrium in a simple force model?

Please select an answer first.

Correct answer: D

The correct answer is The net force is zero..

  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.

Equilibrium means the vector sum of forces is zero; the object can be at rest or move at constant velocity.

5. QuestionMultiple choice

What is air resistance?

Please select an answer first.

Correct answer: A

The correct answer is A friction-like force from air that opposes motion through the air.

  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.

Air resistance depends on motion through air and generally acts opposite the direction of movement.

6. QuestionMultiple choice

What force does a table exert on a book resting on it?

Please select an answer first.

Correct answer: B

The correct answer is An upward normal 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 table provides an upward support force that balances the books downward weight.

7. QuestionMultiple choice

What is static friction?

Please select an answer first.

Correct answer: C

The correct answer is Friction that prevents two surfaces from starting to slide relative to each other.

  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.

Static friction adjusts as needed up to a limit to prevent the start of sliding.

8. QuestionMultiple choice

A box is pushed right with 20 N while friction pushes left with 20 N. What can the box do?

Please select an answer first.

Correct answer: D

The correct answer is Remain at rest or move at constant velocity..

  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.

Equal opposite forces give zero net force, so there is no acceleration.

9. QuestionMultiple choice

Why do tires have tread patterns?

Please select an answer first.

Correct answer: A

The correct answer is Tread can increase useful friction and improve traction with the road..

  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.

Traction depends on friction, and tread helps maintain contact under many conditions.

10. QuestionMultiple choice

Which change would most likely increase the acceleration of a cart?

Please select an answer first.

Correct answer: B

The correct answer is Increase the net force while keeping the mass constant..

  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.

From F = ma, greater net force with unchanged mass produces greater acceleration.

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