Work Energy and...

Two bodies traveling with velocity $$20ms^{-1}$$ and $$40ms^{-1}$$ have same K.E. If the mass of the body having velocity $$40ms^{-1}$$ is 8 kg the mass of other body is 

A body of mass 2$$\mathrm { Kg }$$ moving (initially) with 10$$\mathrm { m } / \mathrm { s }$$ is acting upon by a resultant constar which is opposite to its initial velocity. Its speed decreases to 4$$\mathrm { m } / \mathrm { s }$$ in 1 s. Then the force 

A body of mass 1 kg falls from rest through the air, a distance of 200 m and acquires a speed 50 m/s. Work done against air friction is 

 A block of mass m is oscillating on smooth between two light springs of spring constant K separated by a distance I colliding elastically with the spring.If the velocity of the blocks is increased by an external impulse when it is not touching either of the spring then time period.

A perfectly elastic ball falls on a horizontal floor from a height in a time $$t$$. It will hit the floor again after a time $$t'$$. The ratio of $$t'$$ and t is 

As shown in figure, ball of of mass $$m \,kg$$  is suspended by a string $$\ell \,cm$$ long. Keeping the string always taut, the ball describes a horizontal circle of radius $$\dfrac{\ell}{2}$$. Calculate the angular speed.

A man of mass 20 kg is running in a straight line with velocity 10 m/s. What is value of his kinetic energy?

A body of mass $$8\ kg$$ collides elastically with a stationary mass of $$2\ kg$$. If initial $$KE$$ of moving mass be $$E$$, the kinetic energy left with it after the collision will be:

A rubber band of length $$\lambda$$ has a stone of mass $$m$$ tied to its one end. It is whirled with speed $$v second$$ that the stone described a horizontal circular path. The tension $$T$$ in the rubber band is -

A ball of mass $$m_{1}$$ is moving with velocity $$v$$. It collides head on elastically with a stationary ball of mass $$m_{2}$$. The velocity of ball becomes $$\dfrac{v}{3}$$ after collision, then the value of the ratio $$\dfrac{m_{2}}{m_{1}}$$ is: