(a) The rate of doing work is called as the power. The SI unit of power is Watt denoted by W.
1 Watt is the power of appliances that consume the energy at the rate of 1 joule per second
(b) Given
Mass of brick = 2.5 kg
⇒ Weight = mg = 2.5×10 = 25 N
Weight of 10 bricks = 25×10 = 250 N
Height (h) = 20 m
Time (t) = 50 s
Power = \(\frac{Work\,done}{Time\,taken}\)
⇒ Power = \(\frac{mgh}{t}\) = \(\frac{250\times20}{50}\)
= \(\frac{5000}{50}\) = 100 W
Power spent in carrying bricks is 100 Watt.