Advertisements
Advertisements
प्रश्न
How long should an electric motor, of power 2 H.P. operate, so as to pump 5 m3 of water from a depth of 15m. [Take g = 10 N kg−1]
Advertisements
उत्तर
Mass of water = v × d = 5m3 × 1000 kg m−3 = 5000 kg.
Height = 15 m, t = ?, g = 10 N kg−1
P = 2 H.P. = 2 × 750 = 1500 W
Work done in operating electric motor = P × t = 1500 W × t
Work done in raising water = mgh = 5000 × 10 × 15 = 750000 J
1500 × t = 750000 J
t = 500 seconds.
APPEARS IN
संबंधित प्रश्न
Power spent by a body depends on the time for which it does work.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
What do you mean by degradation of energy?
How much work is done by the gravitational force of earth acting on a satellite moving around it in a circular path? Give reason for your answer.
A body does 20 J of work in 10 s. What is its power?
State the energy changes which take place when A stone dropped from the top of a cliff reaches the ground after some time.
A force is applied on a body of mass 20 kg moving with a velocity of 40 ms−1. The body attains a velocity of 50 ms−1 in 2 seconds. Calculate the work done by the body.
A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?
