Work-Energy Theorem

You lift a suitcase from the floor and keep it on a table.

• The work done by you on the suitcase does not depend on the path taken by the suitcase.

• The work done by you on the suitcase depends on the path taken by the suitcase

• The work done by you on the suitcase is the same as the work done by gravity on the suitcase

• The work done by you on the suitcase depends upon the time you took to lift and keep it on the table.

Which of the following is correct ?

• The work done by a non-conservative force does not depend upon the path taken.

• Work done by gravity is always negative

• If the work done by non-conservative forces is zero, then the mechanical energy of the system remains conserved

• Work done by friction is always negative.

Statement 1: Work done by all the forces on a body is equal to change in its kinetic energy.

Statement 2: Energy can neither be created nor destroyed.

• Both statements are correct and Statement 2 is the correct explaination of Statement 1.

• Both statements are correct but Statement 2 is NOT the correct explaination of Statement 1

• Only Statement 1 is correct

• Only Statement 2 is correct

A ball of mass 2 kg is thrown vertically upward with a speed 20 m/s and it reaches a maximum height of 15 m. Find the work done by air friction on the ball during this journey. Take g = 10 m/s2

• 50 J

• 100 J

• 150 J

• -100 J

Consider the situation shown in the figure. Initially the spring is unstretched when the system is released from rest. Assuming no friction in the pulley, the maximum

elongation of the spring is

• $\frac{mg}{K}$

• $\frac{2mg}{K}$

• $\frac{3mg}{K}$

• $\frac{4mg}{K}$

A particle moves under the effect of a force F = cx from
x = 0 to x = x1. The work done in the process is

•  $cx_1^2$  

•  $\frac{1}{2}cx_1^2$  

•  $cx_1^3$  

•  $\frac{1}{2}cx_1^3$  

A block of mass m slides down along the surface of the

bowl (radius R) from the rim to the bottom. The velocity

of the block at the bottom will be

• $\sqrt{gR}$

• $\sqrt{\pi gR}$

• $\sqrt{2gR}$

• $2\sqrt{\pi gR}$

Statement 1: In the figure show, work done by tension due to string is zero when the ball is allowed to fall a height h

Statement 2: Tension is non-conservative in nature.

• Both statements are correct and Statement 2 is the correct explaination of Statement 1.

• Both statements are correct but Statement 2 is NOT the correct explaination of Statement 1

• Only Statement 1 is correct

• Only Statement 2 is correct