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Newton's Laws Introduction Practice Tests

These Grade 8 Science practice tests cover Newton's First, Second, and Third Laws, inertia, balanced and unbalanced forces, net force, F = ma, acceleration, action-reaction pairs, force diagrams, and safety applications.

Skills covered

  • Explaining inertia and constant velocity with Newton's First Law
  • Using F = ma to connect force, mass, and acceleration
  • Identifying action-reaction pairs on different interacting objects
  • Reading force diagrams and calculating net force and acceleration
  • Applying Newton's Laws to vehicles, sports, rockets, walking, and safety equipment

How to use these practice tests

First identify the object being analyzed and draw the forces acting on it. Add the forces with direction, decide whether the net force is zero, and then apply the appropriate Newton law or F = ma relationship.

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

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Grade 8 Newtons Laws Introduction Practice Tests

Practice Grade 8 Science questions about Newtons First, Second, and Third Laws, inertia, net force, acceleration, force pairs, diagrams, and applications.

Choose the best answer for each question. Identify the Newton law, track force directions and objects, and use F = ma when calculation is needed.

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

A data table shows a 10 N net force on a 2 kg cart and a 20 N net force on the same cart. What should happen to acceleration?

Please select an answer first.

Correct answer: A

The correct answer is It should double from 5 m/s² to 10 m/s²..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

With mass fixed, F = ma means doubling net force doubles acceleration.

2. QuestionMultiple choice

Which data pattern supports Newtons Second Law for a fixed mass?

Please select an answer first.

Correct answer: B

The correct answer is As net force increases, acceleration increases in direct proportion..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

Direct proportionality between force and acceleration is predicted by F = ma when mass is fixed.

3. QuestionMultiple choice

In an investigation of how mass affects acceleration, what should remain controlled?

Please select an answer first.

Correct answer: C

The correct answer is The applied net force and the surface conditions.

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

A fair investigation changes mass while keeping the net force and other important conditions consistent.

4. QuestionMultiple choice

Which statement gives a safe application of Newtons Laws?

Please select an answer first.

Correct answer: D

The correct answer is A seat belt and airbag provide forces that change passenger motion over a longer time during a crash..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

Safety systems manage the change in motion and reduce harmful average forces.

5. QuestionMultiple choice

Why does a heavier object require more net force for the same acceleration?

Please select an answer first.

Correct answer: A

The correct answer is Its greater mass means greater inertia in F = ma..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

The force required equals mass multiplied by acceleration, so more mass needs more force for the same acceleration.

6. QuestionMultiple choice

A student says, "A moving object must have a net force in the direction of motion." What is the best correction?

Please select an answer first.

Correct answer: B

The correct answer is An object can move at constant velocity with zero net force..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

Motion can continue without acceleration when forces are balanced, as described by the First Law.

7. QuestionMultiple choice

A cart has 8 N east, 3 N west, and 2 N west. What is the net force?

Please select an answer first.

Correct answer: C

The correct answer is 3 N east.

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

The total westward force is 5 N, so 8 N east minus 5 N west leaves 3 N east.

8. QuestionMultiple choice

Which model best explains a swimmer moving forward?

Please select an answer first.

Correct answer: D

The correct answer is A force diagram or interaction model showing the swimmer pushing water backward and water pushing forward..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

The interaction between swimmer and water is the relevant action-reaction model.

9. QuestionMultiple choice

Which explanation corrects the misconception that action and reaction forces cancel each other on one object?

Please select an answer first.

Correct answer: A

The correct answer is The pair acts on different objects, so the net force on each object must be analyzed separately..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

Third Law pairs are equal and opposite but act on two different objects.

10. QuestionMultiple choice

What is the best evidence-based conclusion after measuring force and acceleration?

Please select an answer first.

Correct answer: B

The correct answer is The measured acceleration changes with net force as predicted by F = ma, within experimental limits..

  1. Identify the law or force: Decide whether the situation demonstrates inertia, the force-mass-acceleration relationship, or an action-reaction pair.
  2. Track the objects and directions: List the forces, identify which object receives each force, and determine the net force and direction when needed.
  3. Apply the equation or model: Use F = ma, a force diagram, data, or a real-world example to check that the explanation matches Newton law.

A sound conclusion compares measured patterns with the model and acknowledges experimental limits.

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