A bullet of mass 10g leaves a rifle at an initial velocity of 1000m/s and strike the earth at the same level with a velocity of 500m/s. The work done in joule to overcome the resistance of air will be

A stone is thrown at an angle of 45^o to the horizontal with kinetic energy K. The kinetic energy at the highest point is

The identical balls A and B moving with velocities + 0.5 m/s and -0.3 m/s respectively collide head on elastically. The velocity of the balls A and B after collision will be respectively

A child swinging  a swing. Minimum and maximum heights of swing from earth’s  surface are 0.75 m and 2m respectively. The maximum velocity of this swing is 

A force acts on a 3.0 g particle in such a way that the position of the particle as a function of time is given by  x = 3 t – 4 t ² +  t ^3, where x is in meter and  t  in second. The work done during the first 4 s is 

A metal ball of mass 2kg moving with a velocity of 36 km/h has a head on collision with a stationary ball of mass 3 kg. If after the collision, the two balls move together, the loss in kinetic energy due to collision is 

An explosion blows a rock into three parts. Two parts go off at the right angles to each other. These two are, 1kg first part moving with a velocity of 12 ms^-1 and 2kg second part moving with  a velocity of 8ms^-1. If the third part flies off with a velocity of 4ms^-1, its mass would be 

A force F acting on an object varies with distance x as shown here. The force is in newton and x is in metre. The work done by the force in moving the object x = 0 to x = 6m is

300 J of work is done in sliding a 2kg block up an inclined plane of height 10 m. Taking g = 10 m/s², work done against friction is

A ball of mass 2 kg and another of mass 4kg are dropped together from a 60 ft tall building. After a fall of 30 ft each towards earth, their respective kinetic energies will be in the ratio of