# Lesson Worksheet: Mechanical Work Physics • 9th Grade

In this worksheet, we will practice calculating the work done by a force that acts on an object over a distance.

**Q1: **

What average force must be applied to move a computer’s mouse by 0.30 m if this force does 0.75 J of work?

**Q2: **

2,240 J of work is done to a bookcase being pushed by a constant force of 1,600 N. How far is the bookcase pushed by the force?

**Q3: **

A force of 320 N is continually applied to push a cart through a supermarket parking lot. If the cart is pushed for a distance of 15 meters, how much work was done on the cart?

**Q4: **

A 25 N force acts continuously on an object to move it 7.2 m. How much work is done by the force?

**Q5: **

A force does 480 J of work pushing an object 32 m. What is the magnitude of the force?

**Q6: **

How much work is done by a 12 N force acting on an object and moving it a distance of 1.5 m?

**Q7: **

54 J of work is done when pushing an initially stationary wheeled desk of mass 48 kg across the floor of a hall. The desk is moved halfway across the 30 m length of the hall in a time of 20 seconds and then released. The friction of the wheels with the hall’s floor is negligible.

How much work is done per meter that the desk is moved?

What is the average acceleration of the desk over the distance that it moves?

What is the velocity of the desk when it is released?

**Q8: **

An average force of 6,250 N is applied by a car’s wheels while the car moves a distance of 880 m. The car’s engine does 10 megajoules of work to move the car. How much work, in megajoules, was done that did not involve moving the car, such as moving the air around the car, moving parts of the road surface, and heating parts of the car?

**Q9: **

Which of the following formulas correctly shows the relationship between the magnitude of a force, the work done by that force, and the distance moved in the direction of the applied force by the object that the force is applied to?

- A
- B
- C
- D
- E

**Q10: **

A 650 N constant force is applied by a
traveler in a winter landscape to pull a sled of mass
125 kg a distance of
1.4 m across a frozen lake. While the
sled is being dragged, it accelerates at an average rate of
0.12 m/s^{2}.

How much work is done in total moving the sled across the lake?

How much work is done to accelerate the sled?

The sled was at rest before the traveler started to pull it across the lake. What is the velocity of the sled just after it has crossed the lake? Round your answer to two decimal places.