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Force and motion Quiz for Grade 8

10 science questions on force and motion with answers, written for Grade 8. Use it as it is, change any question, print it with an answer key, or give it online and let it grade itself.

1.
What is the unit of force in the International System of Units (SI)? (Multiple choice)
  1. Pascal
  2. Joule
  3. Newton
  4. Watt
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Newton

Force is measured in Newtons, named after Isaac Newton.
2.
Which of the following best describes Newton's First Law of Motion? (Multiple choice)
  1. An object in motion stays in motion unless acted upon by a force
  2. For every action, there is an equal and opposite reaction
  3. Force equals mass times acceleration
  4. Energy cannot be created or destroyed
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An object in motion stays in motion unless acted upon by a force

Newton's First Law states that objects maintain their state of motion unless a force changes it.
3.
If you push a box and it does not move, what can you say about the forces acting on it? (Multiple choice)
  1. There is no force acting on the box
  2. The forces are balanced
  3. The forces are unbalanced
  4. The box has no mass
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The forces are balanced

Balanced forces mean no change in motion, so the box stays still.
4.
Friction always acts in the direction opposite to motion. (True or false)
  1. True
  2. False
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True

Friction opposes the relative motion between surfaces.
5.
An object with greater mass will accelerate more than an object with smaller mass if the same force is applied to both. (True or false)
  1. True
  2. False
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False

Greater mass results in less acceleration for the same force, according to F=ma.
6.
Name the force that pulls objects toward the center of the Earth. (Identification)
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Gravity

Gravity is the force attracting objects toward Earth.
7.
The formula to calculate force is _____ = mass × acceleration. (Fill in the blank)
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Force

Force equals mass times acceleration according to Newton's Second Law.
8.
Which of the following increases when a car speeds up? (Multiple choice)
  1. Acceleration
  2. Friction
  3. Mass
  4. Force of gravity
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Acceleration

Acceleration is the rate of change of velocity when speeding up.
9.
Match each term with its correct definition. (Matching type)
1. Inertia
A. Resistance to change in motion
2. Velocity
B. Force opposing motion
3. Friction
C. Change in velocity over time
4. Acceleration
D. Speed with direction
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1 = Resistance to change in motion; 2 = Speed with direction; 3 = Force opposing motion; 4 = Change in velocity over time

Each term matches its fundamental physics definition.
10.
List three factors that affect the amount of friction between two surfaces. (Enumeration)
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Surface roughness, Normal force, Type of materials

Friction depends on surface roughness, normal force, and material types.