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Questions
state the unit of energy.
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Solution
The SI unit of work is ‘joules’ and the CGS unit is ‘erg’.
RELATED QUESTIONS
An electron emitter must have _____________ work function and ___________ melting point.
How is work related to energy?
A boy of weight 40 kgf climbs up the 15 steps, each 15 cm high in 10 s and a girl of weight 20 kgf does the same in 5 s. Compare:
- the work done, and
- the power developed by them. Take g = 10 N kg-1.
Write the formula for work done on a body when the body moves at an angle to the direction of force. Give the meaning of each symbol used.
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. If the value of g be 10 m/s2, the work done by the girl against the gravitational force will be :
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.
Give an example
Light energy changes to electrical energy.
A water pump raises 50 kg of water through a height of 25 m in 5s. Calculate the power supplied by the pump (Take: g = 10 N kg−1).
