# Worksheet: Mechanical Work

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/s2.

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.

Q11:

A carer does 36 J of work in 24 s to push a baby carriage at a speed of 0.25 m/s. What average force does the carer apply on the baby carriage?

Q12:

The work done on an object to move it some distance is shown in the graph. What force is applied to the object over the first 4 m that it moves?

What force is applied to the object when it is moving from 4 m to 7 m away from its position where the force was initially applied?

What force is applied to the object when it is moving from 7 m to 10 m away from its position where the force was initially applied?

What average force is applied to the object when it is moving from 3 m to 9 m away from its position where the force was initially applied?

Q13:

A constant force pushes an object for 25 m, as shown in the diagram. How much work is done by the force? Q14:

A person pushes a metal crate a distance of 35 m across ice that has negligible friction, applying a constant force of 48 N, as shown in the diagram. When the crate reaches the edge of the ice, it passes onto sand and the person continues pushing with the same constant force as they applied while on the ice. The crate travels 14 m across the sand before coming to rest. What is the net force acting on the crate as it moves across the sand? Q15:

The force applied to an object as it is moved over a distance is shown in the graph. What work is done to the object over the first 5 m that the object moves?

• A250 J
• B100 J
• C500 J
• D25 J
• E20 J

What work is done to the object when moving from 5 m to 8 m away from the position of the object when the force was initially applied?

• A33 J
• B300 J
• C250 J
• D100 J
• E1,300 J

Q16:

A block of ice of mass 20 kg was sliding on a smooth horizontal surface for a distance of 10 m. The work done by the weight of the block is .

• A20 J
• B0 J
• C2,000 J
• D200 J

Q17:

The given graph represents the relation between the net force, , acting on a body moving in a certain direction and the displacement, , covered by the body in the direction of motion, so the total work done by this force on the body is . • A37.5 J
• B67.5 J
• C90 J
• D45 J

Q18:

Which of the following is the correct dimension of the physical quantity work?

• A
• B
• C
• D

Q19:

A lift of weight 11,760 N carrying a group of people of combined mass 195 kg is lifted to the top floor of a building which is 24 m vertically from the ground. Calculate the work needed to lift the whole system. Let .

• A J
• B J
• C J
• D J

Q20:

A worker is pushing a trolley on a horizontal smooth surface for a distance of 0.2 km using a handle, as shown in the figure. The worker does work of J by pushing the trolley with a force in the direction of the handle. Calculate the aforementioned force. • A25 N
• B12 N
• C15 N
• D20 N

Q21:

In the figure shown, what is the work done by the force to push the cart upwardly from the ground to the top of the inclined plane? • A1,000 J
• B1,500 J
• C2,000 J
• D500 J

Q22:

A car of mass 1,200 kg climbs a ramp of length 120 m as shown in the diagram. What is the total work done by the car against gravity ? Let . • A J
• B J
• C J
• D J

Q23:

What is the ratio between gravitational acceleration on Earth’s surface and that on Mars’s surface? Take the mass of Earth to be kg, Earth’s radius to be m, Mars’s mass to be kg, and Mars’s radius to be m.

• A450.55
• B2.62
• C0.38
• D0.0022

Q24:

A force acting on a body and the displacement moved by the body due to the force are shown in the diagram. Calculate the work done by the force. • A1.5 J
• B J
• C J
• D0.5 J

Q25:

A body is thrown vertically upwards. Which of the following graphs correctly shows the relation between the body’s kinetic energy and its height?

• A • B • C • D 