Advertisements
Advertisements
प्रश्न
A man raises a box of mass 50 kg to a height of 2 m in 20 s, while another man raises the same box to the same height in 50 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1
Advertisements
उत्तर
Mass of box m = 50 kg
Height to which box is raised h = 2m
(i) Work done by each man = mgh
= 50 × 10 × 2
= 1000 J
∵ Work done is independent of time taken
∴ Ratio of work done = 1 : 1
(ii) `"Power in first case"/"Power in second case" = (w/t_1)/(w/t_2)`
= `(1000/(20 s))/(1000/(50 s))`
= `50/20`
= 5 : 2
APPEARS IN
संबंधित प्रश्न
A man having a box on his head, climbs up a slope and another man having an identical box walks the same distance on a levelled road.
Who does more work against the force of gravity and why?
Name the quality which is measured in kWh.
A body of mass m is moving with a uniform velocity u. A force is applied on the body due to which its velocity changes from u to v. How much work is being done by the force?
What is meant by a rotatory motion? Give one example.
What is the work done when the force on the object and the displacement of the object are perpendicular to each other?
An engine does 54,000 J of work by exerting a force of 6000 N on it. What is the displacement in the direction of the force?
A man spends 7.4 kJ energy in displacing a body by 74 m in the direction in which he applies force, in 2.5 s. Calculate the power spent (in H.P) by the man.
What happens to the power if the time for doing work is reduced from t second to t/10 second?
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 )
