Advertisements
Advertisements
Question
The average work done by a human heart while it beats once is 0.5 J. Calculate the power used by heart if it beats 72 times in a minute.
Advertisements
Solution
P = `(W.D)/"time"`
W.D in 1 heartbeat = 0.5 J
W.D in 72 heartbeats = 0.5 × 72 = 36 J
Time = 1 minute = 60s
∴ P = `(WD)/t = 36/60 = 6/10` = 0.6 W
As a result, the power consumed by the heart is 0.6 W.
APPEARS IN
RELATED QUESTIONS
A body is moving unidirectionally under the influence of a source of constant power. Its displacement in time t is proportional to ______.
The S.I. unit of power is ..........
1 H.P. = .........
Match the following
| column A | Column B |
| A stone at a height | power |
| A Moving ball | joule |
| Energy | work done in 1 s |
| Power | potential energy |
| Watt | kinetic energy |
1 H.P. is equal to
It takes 20 s for a girl A to climb up the stairs while girl B takes 15 s for the same job. Compare the work done .
Differentiate between watt and watt hour.
An electric heater of power 3 kW is used for 10 h. How much energy does it consume? Express your answer in
- kWh,
- joule.
Arrive at an expression for power and velocity. Give some examples for the same.
A ball with a velocity of 5 ms−1 impinges at an angle of 60˚ with the vertical on a smooth horizontal plane. If the coefficient of restitution is 0.5, find the velocity and direction after the impact.
A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency, the work done by the motor in one rotation will be
An engine develops 20 kW power. How much time will it take to lift a mass of 200 kg to a height of 50 m? (g = 10 m/s2)
An engine pumps up 200 kg of water through a height of 20 m in 10 seconds. If the efficiency of the engine is 80%. Calculate the power of the engine.
Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g = 10m/s2)
Calculate the power spent by a crane while lifting a load of mass 2000 kg, at velocity of 1.5 ms-1. (g = 10 ms-2)
Unit of power used in mechanical engineering is ______.
