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A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
A coolie does no work against the force of gravity while carrying a luggage on a road.
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
When is the work done by a force on a body : (a) positive, (b) negative, and (c) zero?
A boy tries to push a truck parked on the roadside. The truck does not move at all. Another boy pushes a bicycle. The bicycle moves through a certain distance. In which case was the work done more : on the trick or on the bicycle? Give a reason to support your answer.
The work done on an object does not depend on ______.
Is the motion of moon around the earth in circular path an accelerated motion?
A man lifts a mass of 10 kg from the floor to a shelf 4 meter high. If g = 10 ms-2, what is the work done?
Define 'joule'.
A machine raises a load of 750 N through a height of 16 m in 5s. calculate:
(i) work done by machine,
(ii) power at which the machine works.
(a) Define power and name its unit.
(b) A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed.
Fill in the boxe to show the corresponding energy transformation.
Can two agents, doing the same work, have different power?
State the amount of work done by an object when it moves in a circular path for one complete rotation. Give a reason to justify your answer.
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
A wind-mill is lifting water from a well.
A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is ______.
