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प्रश्न
For the following scenario, state whether the work done by gravity is positive, negative, or zero.
A person climbs a ladder.
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उत्तर
Negative work is done.
Explanation:
When a person climbs a ladder (upward), the displacement covered by the person is opposite to the direction of the force of gravity (downward), so the work done on the person by the force of gravity is negative.
संबंधित प्रश्न
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What do you mean by a centrifugal force?
In which one of the following cases is the work done more? When the angle between the direction of motion and that of the force is (i) 90° (ii) 0°.
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.
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.
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 )
