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प्रश्न
Give one example in which a force does zero work.
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उत्तर
Work done by the earth on a satellite moving around the earth is zero, as the direction of the motion of the satellite is always perpendicular to the direction of the gravitational force.
संबंधित प्रश्न
Why is a jack screw provided with a long arm?
A machine raises a load of 750 N through a height of 16 m in 5 s. calculate:
- energy spent by machine,
- power at which the machine works.
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
What are the quantities on which the amount of work done depends? How are they related to work?
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A body of mass 60 kg has the momentum 3000 kgm/s-1. Calculate: the speed of the body.
In the following case write yes, if the work is being done and no if no work is being done.
A boy climbing up a staircase.
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A coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground.
(i) Calculate the mechanical advantage of the inclined plane. (ii) Calculate the effort applied by the coolie.
(iii) In actual practice, the coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
An electric motor of power 100 W is used to drive the stirrer in a water bath. If 50% of the energy supplied to the motor is spent in stirring the water. Calculate the work done on the water in one minute.
