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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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5. Test

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

A data table shows 10 N east and 4 N west acting on a cart. What is the net force?

Please select an answer first.

Correct answer: A

The correct answer is 6 N east.

  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.

Opposite forces subtract, so 10 N east minus 4 N west gives 6 N east.

2. QuestionMultiple choice

Which graph best represents constant speed on a distance-time graph?

Please select an answer first.

Correct answer: B

The correct answer is A straight line with a constant positive slope.

  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 constant positive slope means equal distances are covered in equal time intervals.

3. QuestionMultiple choice

In an experiment about how surface type affects sliding distance, what should be measured?

Please select an answer first.

Correct answer: C

The correct answer is The distance the object travels after starting with the same conditions.

  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 fair test measures the dependent variable, sliding distance, while controlling other conditions.

4. QuestionMultiple choice

Which evidence best supports that a force caused acceleration?

Please select an answer first.

Correct answer: D

The correct answer is The objects velocity changes in the direction of a measured net 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.

A change in velocity aligned with net force is direct evidence of acceleration caused by force.

5. QuestionMultiple choice

A 2 kg cart experiences a net force of 6 N. What is its acceleration using F = ma?

Please select an answer first.

Correct answer: A

The correct answer is 3 m/s².

  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.

Rearrange F = ma as a = F / m, so 6 N / 2 kg = 3 m/s².

6. QuestionMultiple choice

A book rests on a table. Which statement is correct?

Please select an answer first.

Correct answer: B

The correct answer is The upward normal force balances the downward force of gravity..

  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 forces are equal and opposite, so the net force is zero and the book remains at rest.

7. QuestionMultiple choice

What model best represents forces on a falling object before air resistance becomes important?

Please select an answer first.

Correct answer: C

The correct answer is A downward gravity arrow that is larger than any upward resistance arrow.

  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.

Before resistance balances gravity, the downward net force causes the object to accelerate downward.

8. QuestionMultiple choice

Which safety explanation uses force and motion correctly?

Please select an answer first.

Correct answer: D

The correct answer is A helmet increases the time over which the head slows, reducing the average force during impact..

  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.

Increasing stopping time can reduce average force for the same change in momentum, which supports protective equipment.

9. QuestionMultiple choice

Which statement best explains why a heavier cart needs more force for the same acceleration?

Please select an answer first.

Correct answer: A

The correct answer is Greater mass has greater inertia, so more force is needed according to 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.

For the same acceleration, force must increase as mass increases.

10. QuestionMultiple choice

What is the best way to explain a motion result from an investigation?

Please select an answer first.

Correct answer: B

The correct answer is State the pattern, identify the net force, and connect the pattern to evidence and a scientific model..

  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 strong explanation connects observed data with force relationships and evidence.

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