A force applied on a body is represented as $\overrightarrow{F} = 6\stackrel{\wedge }{i} - 8\stackrel{\wedge }{j} + 10\stackrel{\wedge }{k}$

and accelerates it at 1 m/s². The mass of the body is

• 10 kg

• $\sqrt[10]{2} \mathrm{kg}$

• $\sqrt[2]{10} \mathrm{kg}$

• 8 kg

212.

A force $\overrightarrow{\mathrm{F}}$, acting on an electric charge q, in presence of an electromagnetic field, moves the charge parallel to the magnetic field with velocity $\overrightarrow{\mathrm{v}}$ . Then $\overrightarrow{\mathrm{F}}$ is equal to (where $\overrightarrow{\mathrm{E}}$ and $\overrightarrow{\mathrm{B}}$ are electric field and magnetic field respectively)

• $\mathrm{q}\overrightarrow{\mathrm{E}}$

• $\mathrm{q}\left(\overrightarrow{\mathrm{v}} \mathrm{x} \overrightarrow{\mathrm{B}}\right)$

• $\mathrm{q}\left(\overrightarrow{\mathrm{v}} \mathrm{x} \overrightarrow{\mathrm{E}}\right)$

• $\mathrm{q}\overrightarrow{\mathrm{B}}$

A ray of light travels from a medium of refractive index n, to a medium of refractive index n, If angle of incidence is i and angle of refraction is r, then $\frac{\sin \mathrm{i}}{\sin \mathrm{r}}$ is equal to

• n₁

• n₂

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

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

Light waves projected on oil surface show seven colours due to the phenomenon of

• polarization

• refraction

• reflection

• interference

Examine the two statements and carefully and select the answers to these items.

Statement I: A body moving in a circular path is acted upon by the centripetal force.

Statement II : Centripetal force acting on the body is doing work to keep it rotating in the circular path.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I is true but Statement II is false

• Statement I is false but Statement JI is true

If the motion of an object is represented by a straight line parallel to the time axis in a distance-time graph, then the object undergoes

• an accelerated motion

• a decelerated motion

• a uniform non-zero velocity motion

• a zero velocity motion

The working of a microwave oven involves

• absorption of microwaves by matter

• reception of microwaves by optical fibre

• microwave amplification by stimulated emission of radiation

• transmission of microwaves through a metal

Two cars A and B have masses m_A and m_B respectively, with m_A > m_B. Both the cars are moving in the same direction with equal kinetic energy. If equal braking force is applied on both, then before coming to rest

• A will cover a greater distance

• B will cover a greater distance

• both will cover the same distance

• distance covered by them will depend on their respective velocities

If the length of the Equator is about 40000 km and the velocity of rotation is about 1700 km per hour, what would be the velocity of rotation at the Pole?

• Zero

• 850 km/hr

• 1700 km/hr

• 3400 km/hr

A bullet is fired vertically up from a 400 m tall tower with a speed 80 m/s. If g is taken as 10 m/s², the time taken by the bullet to reach the ground will be

• 8 s

• 16 s

• 20 s

• 24 s