Work, power and simple machines

Question 1 of 10

A machine lifts a load of 800 N through 1 m when an effort of 200 N moves through 5 m. Calculate (a) the mechanical advantage, (b) the velocity ratio, (c) the efficiency.

Question 2 of 10

A boy of mass 20 kg climbs stairs 3 m high. Taking g = 10 N/kg, the work he does is ___ J.

Question 3 of 10

Oiling machines can increase their efficiency.

Question 4 of 10

A machine does 4,800 J of work in 20 s. Find its power.

Question 5 of 10

The pivot point of a lever is the

Question 6 of 10

The SI unit of power is the

Question 7 of 10

A boy of mass 40 kg climbs stairs 4 m high. Taking g = 10 N/kg, the work he does is ___ J.

Question 8 of 10

A boy of mass 50 kg climbs stairs 3 m high. Taking g = 10 N/kg, the work he does is ___ J.

Question 9 of 10

A crowbar is an example of a

Question 10 of 10

Simple machines create energy.