Work, energy and power

Question 1 of 10

A student of mass 70 kg runs up a flight of stairs of vertical height 15 m in 20 s. (g = 10 m/s²) (a) Calculate the work done against gravity. (b) Calculate the power developed. (c) Explain why the actual energy used by the student is greater. (d) State the energy changes involved.

Question 2 of 10

Find the kinetic energy of a 5 kg body moving at 10 m/s.

Question 3 of 10

A man carrying a load horizontally at constant speed does no work on the load against gravity because

Question 4 of 10

Doubling the speed of a body doubles its kinetic energy.

Question 5 of 10

The SI unit of power is the

Question 6 of 10

Find the potential energy gained when a 20 kg mass is raised through 2 m. (g = 10 m/s²)

Question 7 of 10

A force of 100 N moves a box 2 m in its own direction. The work done is ___ J.

Question 8 of 10

Power = force × velocity.

Question 9 of 10

A force of 10 N moves a box 10 m in its own direction. The work done is ___ J.

Question 10 of 10

Kinetic energy is given by