# Worksheet: Newton's First Law of Motion

In this worksheet, we will practice using Newton's first law of motion and applying Newton's second law of motion to analyze systems of forces that produce no net acceleration.

**Q2: **

Which of the following statements most correctly describes Newton's first law of motion?

- AAn object will move until a net force acts on the object.
- BAn object will not move unless a net force acts on the object.
- CAn object will change direction if a net force acts on the object.
- DAn object will not change its velocity unless a net force acts on the object.

**Q3: **

A book at rest on a table has a weight of 8 N.

At what rate is the book accelerating?

What is the net force acting on the book?

What magnitude force does the table apply to the book?

**Q4: **

A speck of dust with a mass of 0.25 g in deep space very far from any other objects is at rest. In another completely different part of deep space that is also very far from any other objects, a tiny ice crystal with a mass of 0.75 g moves at a constant speed of 25 m/s.

What is the speck of dust’s rate of acceleration?

What net force acts on the speck of dust?

What is the ice crystal’s rate of acceleration?

What net force acts on the ice crystal?

**Q5: **

A ship with a weight of 7 000 N has both a motor and sails. The ship moves at a constant speed across the surface of the sea. The motor provides a force of 8 500 N and the drag from the water around the ship produces a force of 6 000 N. The wind is blowing in the opposite direction to the motion of the ship, so the sails provide a drag force on the ship.

What is the force on the ship from the wind pushing on its sails?

- A 2 500 N
- B −6 000 N
- C 6 000 N
- D −2 500 N
- E 8 500 N

How many newtons of force does the water underneath the ship apply upward on the ship’s hull?

- A 7 000 N
- B 8 500 N
- C 6 000 N
- D 2 500 N
- E 1 000 N

**Q6: **

A car has a velocity of 25 m/s as it passes a road sign. At that point, the car’s wheels push the car forward with a force of 550 N, and the friction between the car’s wheels and the road applies a force of 550 N in the opposite direction to the car’s motion. What is the velocity of the car 10 seconds after it passes the sign? Assume no other forces act in this time.