Advertisements
Advertisements
Question
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?
Advertisements
Solution
Man having a box on his head who climbs up a slope does more work against the force of gravity because he has more potential energy by virtue of his position i.e., height.
As, P.E. = W.D. = F × S
= mg × h
RELATED QUESTIONS
Differentiate between work and power.
State the condition when a force produces
(i) linear motion.
(ii) rotational motion, in a body.
What do you mean by equilibrium of a body?
A pump is used to lift 600 kg of water from a depth of 75 m in 10s. Calculate:
- The work done by the pump,
- the power at which the pump works, and
- The power rating of the pump if its efficiency is 40%. (Take g = 10m s-2).
`["Hint" : "Efficiency" = "useful power"/"power input"]`
A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes.
How much work each does? Take density of water = 103 kg m-3 and g = 9.8 N kg-1.
In the following case write yes, if the work is being done and no if no work is being done.
A man trying to push a wall.
State the condition when the work done by the force is positive
What is the S.I. unit of work? Define it.
State the C.G.S. unit of work. How it is related to its S.I. unit?
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 )
