Energy & Power Form 3

State the definition of work.

• The rate of doing work

• The product of force and displacement in the direction of the force

• The ability to do work

• The work done to lift an object to a height

What is the S.I. unit for work?

• force, F

• work, W

• newton, N

• joule, J

Figure 1 shows an electromagnetic crane lifting a load weighing 2 500 N to a height of 4 m. Calculate the work done.

A labourer pulled a bucket of cement weighing 300 N from the ground to the first floor of a building using a pulley system. The first floor is 10 m from the ground. What is the work done by the labourer?

Energy is defined as

• The rate of doing work

• The product of force and displacement

• The ability to do work

• Work done divide by time taken

Energy is defined as

• The rate of doing work

• The product of force and displacement

• The ability to do work

• Work done divide by time taken

The S.I. unit for power is

• watt, W

• power, P

• joule, J

• newton, N

Figure 1 shows an electromagnetic crane lifting a load weighing 2 500 N to a height of 4 m. If the time taken by the crane to lift the load is 1.2 minutes, calculate the power of the crane.

State the formula for Gravitational potential energy

A ball bearing of mass 0.2 kg possesses kinetic energy of 3.6 J. What is the velocity, v of the ball bearing?