Advertisements
Advertisements
प्रश्न
A man weighing 700 N runs up a flight of 15 steps, each 20 cm high, in 5 seconds. Calculate the power of the man.
Advertisements
उत्तर
Total height covered = 15 × 20 cm
= 300 cm
= 3 m
Work done = Force × distance
= 700 N × 3 m
= 2100 J
Since the time taken is 5s, the power of the man is
Power = (2100/5) Js−1
= 420 W.
संबंधित प्रश्न
State and define the S.I. unit of work.
One horse power is equal to ______.
Is it possible that no transfer of energy may take place even when a force is applied to a body?
It takes 20 s for a person A of mass 50 kg to climb up the stairs, while another person B of same mass does the same in 15 s. Compare the power developed by the persons A and B.
A bullet fired against a window glass pane makes a hole in it without any cracks while a stone striking the same glass pane smashes it; explain with reason.
A force F when acts on a body, displace it by a distance d in a direction at an angle θ with the direction of the force. Write down the expression for the work done by the force.
State the practical unit mainly used in mechanical engineering and write down its equivalent in watt.
Calculate the work done when:
A car is moved on a rough road through 30 m against a frictional resistance of 75 N.
A force of 1 kgf displaces a body by a distance of 10 cm
(i) in direction of force,
(ii) normal to the force
(iii) at an angle of 60° to the direction of the force.
Calculate the amount of work done in each case. (Take: g = 9.8 ms−2 )
