# Solutions to the Quiz on Newton's Laws

Question 1: If you pull on a 20-kg wagon with a constant force of 80 N.
What is the wagon's acceleration?

• 0.0 m/s2
• 2.0 m/s2
• 4.0 m/s2
• 5.0 m/s2
Explanation: a = F / m = 80 N / 20 kg = 4.0 m/s2

Question 2: If a car runs out of fuel while running, and the engine stops.
The car doesn't stop suddenly because of ........

• speed.
• inertia.
• mass.
• acceleration.

Question 3: Both ends of a piece of rope are pulled by two people in a tug-of-war contest.
If each pulls with a 500-N force, what would be the tension in the rope?

• 0 N
• hard to find
• 500 N
• 250 N

Question 4: Assume that an object's mass get reduced while a constant force acts on it.
In this case, the acceleration .........

• increases.
• decreases.
• stays the same.
• becomes zero.

Question 5: Flying motion of birds is an example of ............

• newton's first law.
• newton's second law.
• newton's third law.
• conservation of energy.

Question 6: Action and reaction pair of forces...............

• cancel each other.
• always act on different bodies.
• are both zero.
• represent a case of conservation of energy.
Answer: always act on different bodies.
Explanation:
If you exert an action force on a small wagon. In response the wagon exerts an equal and opposite reaction force on you.
The action and reaction pair of forces do not cancel each other out.
And the reason is because they were not exerted on the same object.

Question 7: An object in motion tends to remain in motion...............

• because the force is zero.
• is not possible.
• due to energy conservation law.
• without the need of a force.
Answer: without the need of a force.

Question 8: An object in motion tends to remain in motion is an example of ..............

• newton's first law.
• newton's second law.
• newton's third law.
• conservation of energy.

Question 9: Newton's second law focuses on ..............

• speed.
• inertia.
• mass.
• acceleration.

Question 10: Propulsion of fish is an example of..............

• newton's first law.
• newton's second law.
• newton's third law.
• conservation of energy.

Question 11: If you are attracted toward Earth by a 800-N gravitational force.
Then Earth is attracted towards you with a force of..........

• 0 N
• hard to find
• 400 N
• 800 N

Question 12: Assume a given net force drives an object along a straight-line path.
If the mass were doubled, its acceleration would............

• be half.
• be double.
• be zero.
• stay the same

Question 13: Assumne a boat exerts a force of 4,000 N on a jetski that accelerates at 2 m/s2.
What is the mass of the jetski?

• 0 kg.
• 1,000 kg.
• 2,000 kg.
• 3,000 kg.