Question
What is a lever?
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Answer
A lever is a special case of the application of the law of moments. It is a rigid bar, straight or bent, which is capable of rotation about a fixed point or a fixed-line, called the axis of rotation. This fixed point or the axis of rotation is called the fulcrum. An effort E is applied at point A of the lever to overcome resistance (or load) at another point B, as shown in the diagram.
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$(ii)$ An electric pump is $60 \%$ efficient and is rated $2 HP$ . Calculate the maximum amount of water it can lift through a height of $5 m$ in $40 s .\ [$Take $g =10 ms^{-2}$ and $1 HP =750 W$ ]
$(iii)$ In a hydroelectric power station, $1000 \ kg$ water is allowed to drop through a height of $100 m$ in $1s$ . If the conversion of potential energy to electric energy is $60 \%$, calculate the power output in $kW ($take $g =10 m / s ^2).$
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Specific latent beat of fusion of ice $=336 Jg ^{-1}$.
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Specific heat capacity of water $=4.2 Jg ^{-1}{ }^{\circ} C ^{-1}$
Specific latent heat of fusion of ice $=336 Jg ^{-1}$
(ii) A piece of ice of mass 60 g is dropped into 140 g of water at $50^{\circ} C$. Calculate the final temperature of water when all the ice has melted. (Assume no heat is lost to the surrounding)
Specific heat capacity of water $=4.2 Jg ^{-1} K^{-1}$.
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