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प्रश्न
State the energy changes which take place when A piece of magnesium wire is burnt in a jar of oxygen.
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उत्तर
Chemical energy (chemical reaction) → Heat energy (burning)
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संबंधित प्रश्न
Fill in the blank with suitable word :
1 joule is the work done when a force of 1 __________ moves an object through a distance of one __________ in the direction of __________.
P, Q and R are three forces which act as shown in fig.
The point O lies in the same plane. Given, P = Q = R = 10N
(i) Which force has the least moment about O? Give a reason.
(ii)Which force has the greatest moment about O? Give a reason.
Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly?
A block of mass 30 kg is pulled up a slope, as shown in diagram with a constant speed, by applying a force of 200 N parallel to slope.
A and B are initial and final positions of block.
(i) Calculate the work done by force in moving the block from A to B.
(ii) Calculate P.E. gained by block. [g=10ms-2]
How long should an electric motor, of power 2 H.P. operate, so as to pump 5 m3 of water from a depth of 15m. [Take g = 10 N kg−1]
Work done by this force at any instant is ______.
