Which one of the following is not a conservative force 

(1) Gravitational force

(2) Electrostatic force between two charges

(3) Magnetic force between two magnetic dipoles

(4) Frictional force

Work done in raising a box depends on

(1) How fast it is raised

(2) The strength of the man

(3) The height by which it is raised

(4) None of the above

If the increase in the kinetic energy of a body is 21%, then the increase in the momentum will be:
1. 22%
2. 44%
3. 10%
4. 300%

If a body of mass 200 g falls from a height 200 m and its total P.E. is converted into K.E. at the point of contact of the body with earth surface, then what is the decrease in P.E. of the body at the contact (g = 10 m/s²) 

(1) 200 J

(2) 400 J

(3) 600 J

(4) 900 J

The kinetic energy of a body of mass 2 kg and momentum of 2 Ns is 

(1) 1 J

(2) 2 J

(3) 3 J

(4) 4 J

A particle of mass m at rest is acted upon by a force F for a time t. Its Kinetic energy after an interval t is 

(1) $\frac{F^2{t}^2}{m}$

(2) $\frac{F^2{t}^2}{2m}$

(3) $\frac{F^2{t}^2}{3m}$

(4) $\frac{Ft}{2m}$

If a man increase his speed by 2 m/s , his K.E. is doubled, the original speed of the man is 

(1) $(1+2\sqrt{2})m/s$

(2) 4 m/s

(3) $(2+2\sqrt{2})m/s$

(4) $(2+\sqrt{2})m/s$ 

The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant K and compresses it by length L. The maximum momentum of the block after collision is 

(1) Zero

(2) $\frac{M{L}^2}{K}$

(3) $\sqrt{MK}L$

(4) $\frac{K{L}^2}{2M}$

Two springs have their force constant as k₁ and $k_2(k_1>k_2)$. When they are stretched by the same force 

(1) No work is done in case of both the springs

(2) Equal work is done in case of both the springs

(3) More work is done in case of second spring

(4) More work is done in case of first spring

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