1. A sprinter of mass 70 kg starts from rest and reaches a top speed of 9 m/s in 3 seconds. The maximum kinetic energy of the sprinter is 2835 J. Calculate the average power developed by the sprinter during this time. W
2.
(a). What is the weight of the loaded bucket? N
(b). How much work is done by the worker in raising the bucket to a height of 5 m? J
(c). What is the gain in the gravitational potential energy of the bucket? J
3. A stone of mass 0.2 kg is thrown vertically upwards. The stone reaches its highest point after it has moved through a distance of 5 m.
(a). What is the kinetic energy of the stone at it highest point? J
(b). Calculate the gravitational potential energy gained by the stone when it is at its highest point? J
4 (Credit). An electric motor is used to winch a load of mass 50 kg at constant speed vertically upwards through a height of 20 m. The power delivered by the motor is 400 W.
(a). What is the weight of the load? N
(b). What is the gain in the gravitational potential energy of the load? kJ
(c). How long does it take to winch up the load? s
5 (Credit).
a. A truck of mass 1500 kg travelling at 25 m/s
b. A car of mass 1500 kg travelling at 20 m/s
