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प्रश्न
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उत्तर
K.E = `1/2` mv²
60 = `1/2` (30) (v)²
or v² = 4 m/s
or v= 2 m/s
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संबंधित प्रश्न
Differentiate between energy and power.
A weight lifter lifted a load of 200 kgf to a height of 2.5 m in 5 s. Calculate:
- the work done, and
- the power developed by him. Take g = 10 N kg-1
A bullet of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball.
Give one example each in which a force does (a) positive work (b) negative work, and (c) zero work.
Give two examples of couple action in our daily life.
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.
Name the physical quantity whose MKS units are kgm2s-3.
An object is dropped from a height H. when is its
(i) P.E. maximum,
(ii) K.E. maximum,
(iii) P.E. = K.E.?
Give an example
Chemical energy changes to heat energy.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
An engine is pulling a train.
