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Class 9Class 10First YearSecond Year
$A diver weighing 750 \mathrm{~N} dives from a board 10 \mathrm{~m} above the surface of a pool of water. Use the conservation of mechanical energy to find his speed at a point 5.0 \mathrm{~m} above the water surface neglecting air friction.$

$A car mass 800 \mathrm{~kg} traveling at 54 \mathrm{kmh}^{-1} is brought to rest in 60 meters. Find the average retarding force on the car. What has happened to original kinetic energy?$

$An object has 1 \mathrm{~J} of potential energy. Explain what does it mean?$

$When a rocket re-enters the atmosphere its nose cone becomes very hot. Where does this heat energy come from?$

$6.6 Define K.E. and derive its relation.$

$6.10 An electric motor of 1 \mathrm{hp} is used to run water pump. The water pump takes 10 minutes to fill an overhead tank. The tank has a capacity of 800 litres and height of 15 \mathrm{~m} . Find the actual work done by the electric motor to fill the tank. Also find the efficiency of the system.$

$What sort of energy is in the following:(b) Water in a high dam$