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प्रश्न
उत्तर
Horse power is the unit of power. The horsepower used for electrical machines is defined as exactly 746 watt.
Classically, a horse exerting 1 H.P. can raise 330 pounds of coal 100 feet in a minutes, or 33 pounds of coal 1,000 feet in one minute, or, 1,000 pounds 33 feet in one minute.
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संबंधित प्रश्न
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Work is said to be done by a forte only when ................
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.
State two factors on which the work done on a body depends.
A man lifts a mass of 20 kg to a height of 2.5 m. Assuming that the force of gravity on 1 kg mass is 10 N, find the work done by the man.
A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done : by the force applied by the boy?
(a) by the force applied by the boy?
(b) by the gravitational force of earth?
Explain by an example that a body may possess energy even when it is not in motion.
Choose one or more correct alternatives.
For work to be performed, energy must be ______.
- transferred from one place to another
- concentrated
- transformed from one type to another
- destroyed
The work done on an object does not depend on ______.
A boy does work when he pushes against a brick wall. (yes/no).
A boy of mass m climbs up a staircase of vertical height h.
- What is the work done by the boy against the force of gravity?
- What would have been the work done if he uses a lift in climbing the same vertical height?
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
State the energy changes which take place when A toy car with a wound spring moves on ground.
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.
Calculate the work done when:
A 5 kg weight is lifted 10 m vertically. (g = 9.8 m/s2)
A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is ______.
