Work Energy and...

A body of mass m is rotating in a vertical circle of radius 'r' with critical speed. The difference in its K.E. at the top and the bottom is _____.

A spring of force constant $$800 N/m$$ has an extension of $$5 cm$$. The work done in extending it from $$5 cm$$ to $$15 cm$$ is :

A vertical spring of force constant $$100 N/m$$ is attached with a hanging mass of $$10 kg$$. Now an external force is applied on the same so that the spring is stretched by additional $$2m$$. The work done by the force is ($$g= 10 m/s^2$$)

A cone filled with water is whirled in a vertical circle of radius 4 m. What will be the time period of rotation so that water does not fall ?

Two springs of force constants $$  \mathrm{K}_{1}  $$ and $$  \mathrm{K}_{2}  $$ $$ \left(\mathrm{K}_{1}>\mathrm{K}_{2}\right)  $$ are stretched by same force. If $$  \mathrm{W}_{1}  $$ and $$  W_{2}  $$ be the work done stretching the springs then

At the instant speed of block is maximum, the magnitude of force exerted by spring on the block is

In $$10 s$$, a body of $$6 kg$$ mass is dragged $$8 m$$ with uniform velocity across a floor by a steady force of $$20 N$$. The K.E of the body is:

If the kinetic Energy possessed by a man of $$50$$kg is $$625J$$, the speed of man is 

 A ball of mass 3 kg moving with a velocity of 4 m/s undergoes a perfectly- elastic collision with a stationary ball of mass m. After the impact is over, the kinetic energy of the 3 kg ball is 6 J. The possible value of m is/are :

Water is dragged from a well of hepth 30 m using bucket of weight 50kg with water If the weight of the rope is 0.4 kg per metre, the amount of work done is