Advertisements
Advertisements
Question
.A man raises a box of mass 50kg to a height of 2m in 20s, while another man raises the same box to the same height in 50s. Compare:
(i) the work done, and
(ii) the power developed by them.
Advertisements
Solution
(i) Work done to raise the block of mass 50kg is same for both.
(ii) Power= Work done/time. As the time taken by the first man is less therefore power developed is more.
RELATED QUESTIONS
State two factors on which the work done on a body depends.
In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
A boy weighing 25 kgf climbs up from the first floor at height 3 m above the ground to the third floor at height 9m above the ground. What will be the increase in his gravitational potential energy? (Take g = 10 N kg -1)
What are the units of (a) work, and (b) energy?
Complete the following sentences:
The SI unit of work is ....... and of power is .......
(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.
State the energy changes which take place when A stone dropped from the top of a cliff reaches the ground after some time.
A canon ball of mass 500g is fired with a speed of 15m/s-1. Find: its momentum.
