Which one of the following statement is wrong?
1. | When a conservative force does positive work on a body, the potential energy of the body decreases. |
2. | Work done by a body against friction always results in a loss of its kinetic energy. |
3. | The rate of change of the total momentum of a many-particle system is proportional to the sum of the internal forces on the system. |
4. | In an inelastic collision of two bodies, the total linear momentum of the system of two bodies does not change after the collision. |
A body of mass 0.5 kg travels in a straight line with velocity where . What is the work done by the net force during its displacement from x = 0 to x = 2 m?
1. 50 J
2. 45 J
3. 68 J
4. 90 J
A 1 kg block situated on a rough incline is connected to a spring of spring constant as shown in the figure. The block is released from rest with the spring in the unstretched position. The block moves 10 cm down the incline before coming to rest. The coefficient of friction between the block and the incline is:
(Assume that the spring has a negligible mass and the pulley is frictionless.)
1. 0.03
2. 0.14
3. 0.11
4. 0.08