Which of the following graph depicts spring constant k versus length l of the spring correctly

1.
2.
3.
4.

Work done by a frictional force is

1. Negative

2. Positive

3. Zero

4. All of the above

A block of mass 50 kg slides over a horizontal distance of 1 m. If the coefficient of friction between their surfaces is 0.2, then work done against friction is 

1. 98 J

2. 72J

3. 56 J

4. 34 J

A man pushes a wall and fails to displace it. He does:
1. negative work
2. positive but not maximum work
3. no work at all
4. maximum work

A body moves a distance of 10 m along a straight line under the action of a force of 5 N. If the work done is 25 joules, the angle which the force makes with the direction of motion of the body is

(1) 0°

(2) 30°

(3) 60°

(4) 90°

A force $F=(5\hat{i}+3\hat{j})$ newton is applied over a particle which displaces it from its origin to the point $r=(2\hat{i}-1\hat{j})$  metres. The work done on the particle is 

(1) – 7 joules

(2) + 13 joules

(3) + 7 joules

(4) + 11 joules

A uniform chain of length 2m is kept on a table such that a length of 60cm hangs freely from the edge of the table. The total mass of the chain is 4kg. What is the work done in pulling the entire chain on the table?

(1) 7.2 J

(2) 3.6 J

(3) 120 J

(4) 1200 J

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that 

(1) Its velocity is constant

(2) Its acceleration is constant

(3) Its kinetic energy is constant

(4) It moves in a straight line

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

(1) $C{x}_1^2$

(2) $\frac{1}{2}C{x}_1^2$

(3) $C{x}_1$

(4) Zero

A cord is used to lower vertically a block of mass M by a distance d with constant downward acceleration $\frac{g}{4}$. Work done by the cord on the block is 

(1) $Mg\frac{d}{4}$

(2) $3Mg\frac{d}{4}$

(3) $-3Mg\frac{d}{4}$

(4) Mgd