6.1: A man has pulled a cart through 35 m applying a force of 300 N. Find the work done by the man. Ans. (10500 J)


6.2: A block weighing 20 N is lifted 6 m vertically upward. Calculate the potential energy stored in it. Ans. (120 J)


6.3: A car weighing 12 kN has speed of 20 ms⁻¹ . Find its kinetic energy. Ans. (240 kJ)


6.4: A 500 g stone is thrown up with a velocity of 15ms⁻¹. Find its 
(i) P.E. at its maximum height 
(ii) K.E. when it hits the ground Ans. (56.25 J, 56.25 J)


6.5: On reaching the top of a slope 6 m high from its bottom, a cyclist has a speed of 1.5 ms⁻¹. Find the kinetic energy and the potential energy of the cyclist. The mass of the cyclist and his bicycle is 40 kg. Ans. (45 J, 2400 J)



6.6: A motorboat moves at a steady speed of 4 ms⁻¹. Water resistance acting on it is 4000 N. Calculate the power of its engine. Ans. (16 kW)


6.7: A man pulls a block with a force of 300 N through 50 m in 60 s. Find the power used by him to pull the block. Ans. (250W)


6.8: A 50 kg man moved 25 steps up in 20 seconds. Find his power, if each step is 16 cm high. Ans. (100 W)

6.9: Calculate the power of a pump which can lift 200 Kg of water through a height of 6 m in 10 seconds. Ans. (1200 watts)


6.10: An electric motor of 1hP is used to run water pump. The water pump takes 10 minutes to fill an overhead tank. The tank has a capacity of 800 litres and height of 15 m. Find the actual work done by the electric motor to fill the tank. Also find the efficiency of the system. (Density of water = 1000 kgm-3 ) (Mass of 1 litre of water = 1 Kg) Ans. (447600 J, 26.8 %)