A body of mass m is travelling with a velocity u. When a constant retarding force F is applied, it comes to rest after travelling a distances s₁. If the initial velocity is 2u, with the same force F, the distance travelled before it comes to rest is s₂. Then,

• s₂ = 4s₁

• s₂ = 2s₁

• ${\mathrm{s}}_2 = \frac{{\mathrm{s}}_1}{2}$

• s₂ = s₁

A block kept on a rough surface starts sliding when the inclination of the surface is with respect to the horizontal. The coefficient of static friction between the block and the surface is

• sec θ

• sin θ

• tan θ

• cos θ

Two bodies ofmasses m₁ and m₂ are acted upon by a constant force F for a time t. They start from rest and acquire kinetic energies, E₁ and E₂ respectively. Then $\frac{{\mathrm{E}}_1}{{\mathrm{E}}_2}$ is

• $\frac{\sqrt{{\mathrm{m}}_1{\mathrm{m}}_2}}{{\mathrm{m}}_{1 }+ {\mathrm{m}}_2}$

• $\frac{{\mathrm{m}}_1}{{\mathrm{m}}_2}$

• $\frac{{\mathrm{m}}_2}{{\mathrm{m}}_1}$

• 1

4.

The X and Y components of a force F acting at 30° to x-axis are respectively

• $\mathrm{F}, \frac{\mathrm{F}}{\sqrt{2}}$

• $\frac{\mathrm{F}}{\sqrt{2}}, \mathrm{F}$

• $\frac{\mathrm{F}}{2}, \frac{\sqrt{3}}{2}\mathrm{F}$

• $\frac{\sqrt{3}}{2}\mathrm{F}, \frac{1}{2}\mathrm{F}$

Two fixed charges A and B of 5 µC each are separated by a distance of 6 m. C is the mid point of the line joining A and B. A charge Q of −5μC is shot perpendicular to the line joining A and B through C with a kinetic energy of 0.06 J. The charge Q comes to rest at a point D. The distance CD is

• 4 m

• 3 m

• $\sqrt{3} \mathrm{m}$

• $3\sqrt{3} \mathrm{m}$

The dimensional formula of physical quantity is is [M^aL^bT^c]. Then, that physical quantity is

• Spring constant if a = 1, b = −1, c = −2

• surface tension if a= 1, b = 1,c = −2

• force if a = 1, b = 1, c = 2

• angular frequency if a = 0, b = 0, c = − 1

A person throws balls into air vertically upward in regular intervals of time of one second. The next ball is thrown when the velocity of the ball thrown earlier becomes zero. The height to which the balls rise is (Assume, g = 10 ms^-2)

• 20 m

• 5 m

• 10 m

• 7.5 m

A planet moving around sun sweeps area A₁ in 2 days, A₂ in 3 days and A₃ in 6 days. Then, the relation between A₁, A₂ and A₃ is

• 6A₁ = 3A₂ = 2A₃

• 3A₁ = 2A₂ = A₃

• 2A₁ = 3A₂ = 6A₃

• 3A₁ = 2A₂ = 6A₃

Intensity level of sound whose intensity is 10^-8 Wm^-2 is

• 80 dB

• 8 dB

• 4 dB

• 40 dB

Mille is an example for

• emulsion

• inelastic gel

• foam

• elastic gel