Newtons laws of motion worksheet - Free Printable

Let's solve each question step by step and explain the reasoning behind the answers.

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Question 6: According to Newton’s third law of motion, what does every action have?

- Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object exerts an equal and opposite force back on the first object.
- Options:
- a. No reaction
- b. An equal and opposite reaction
- c. The same reaction
- d. A larger reaction

Correct Answer: b. An equal and opposite reaction

Explanation: Newton's Third Law states that forces always occur in pairs, and these pairs are equal in magnitude but opposite in direction. For example, if you push against a wall, the wall pushes back with an equal force in the opposite direction.

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Question 7: If you place a book on your desk, it will remain at rest on your desk unless a force causes it to move. Which of Newton’s law does the example help explain?

- Newton's First Law of Motion (Law of Inertia): An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.
- Options:
- a. Newton’s gravitational force
- b. Newton’s first law of motion
- c. Newton’s second law of motion
- d. Newton’s third law of motion

Correct Answer: b. Newton’s first law of motion

Explanation: The book remains at rest because no external force is acting on it to change its state of rest. This is a direct application of Newton's First Law, which describes inertia.

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Question 8: What is the force of an object equal according to Newton’s second law of motion?

- Newton's Second Law of Motion: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. Mathematically, this is expressed as:
\[
F = ma
\]
where \( F \) is the force, \( m \) is the mass, and \( a \) is the acceleration.
- Options:
- a. Its height added to its speed
- b. Its weight divided by acceleration
- c. Its mass times acceleration
- d. Its width times its speed

Correct Answer: c. Its mass times acceleration

Explanation: According to \( F = ma \), the force acting on an object is equal to the product of its mass and its acceleration. This directly matches option (c).

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Question 9: If you and a friend hold a book, a pencil, a paper clip, and a crayon at the same height in the air, and drop them all, which item will hit the ground with the greatest force?

- Key Concept: When objects are dropped from the same height in a vacuum (ignoring air resistance), they all fall with the same acceleration due to gravity (\( g \approx 9.8 \, \text{m/s}^2 \)). However, the force with which they hit the ground depends on their mass and the acceleration due to gravity.
- Force Calculation: The force with which an object hits the ground can be calculated using \( F = ma \). Since all objects fall with the same acceleration (\( g \)), the object with the greatest mass will hit the ground with the greatest force.
- Mass Comparison:
- Book: Heaviest
- Pencil: Lighter than the book
- Paper clip: Very light
- Crayon: Lighter than the book but heavier than the paper clip

Correct Answer: a. The book

Explanation: The book has the greatest mass among the objects, so it will hit the ground with the greatest force.

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Question 10: If you drop an object, it will fall directly to the ground because of

- Key Concept: When an object is dropped, it falls toward the ground due to the gravitational force exerted by the Earth. Gravity pulls objects toward the center of the Earth, causing them to accelerate downward.
- Options:
- a. Friction
- b. Gravity
- c. Inertia
- d. Work

Correct Answer: b. Gravity

Explanation: Gravity is the force responsible for pulling objects toward the Earth. Without gravity, objects would not fall to the ground when dropped.

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Final Answers:

1. Question 6: b. An equal and opposite reaction
2. Question 7: b. Newton’s first law of motion
3. Question 8: c. Its mass times acceleration
4. Question 9: a. The book
5. Question 10: b. Gravity

Boxed Final Answer:
\[
\boxed{b, b, c, a, b}
\]