11.

A stone of density 2000 kg m^-3 completely immersed in a lake is allowed to sink from rest. If the effect of friction is neglected, then after 4 seconds, the stone will reach a depth of

• 78.4 m

• 39.2 m

• 19.6 m

• 9.8 m

If the average kinetic energy of a molecule of a hydrogen gas at 300 K is E, then the average kinetic energy of a molecule of a nitrogen gas at the same temperature is

• 7 E

• E/14

• E

• E/7

When the voltage and current in a conductor are measured as (100 ± 4) V and (5 ± 0.2) A, then the percentage of error in the calculation of resistance is

• 8 %

• 4 %

• 20 %

• 10 %

The set of physical quantities among the following which are dimensionally different is

• terminal velocity, drift velocity, critical velocity

• potential energy, work done, kinetic energy

• dipole moment, electric flux, electric field

• distintegration constant, frequency, angular velocity

The graph which cannot possibly represent one-dimensional motion is

An aeroplane is flying with a uniform speed of 150 km h^-1 along the circumference of a circle. The change in its velocity in half the revolution (in km h^-1) is

• 150

• 100

• 200

• 300

In uniform circular motion, the centripetal acceleration is

• towards the centre of the circular path and perpendicular to the instantaneous velocity

• a constant acceleration

• away from the centre of the circular path and perpendicular to the instantaneous velocity

• a variable acceleration making 45° with the instantaneous velocity

A man rides a bicycle with a speed of 17.32 ms^-1 East- West direction. If the rain falls vertically with a speed of 10 ms^-1, then the direction in which he must hold his umbrella is

• 30° with the vertical towards East

• 60° with the vertical towards West

• 30° with the vertical towards West

• 60° with the vertical towards East

A body is thrown up with a speed u, at an angle of projection θ. If the speed of the projectile becomes $\frac{\mathrm{u}}{\sqrt{2}}$on reaching the maximum height, then the maximum vertical height attained by the projectile is

• $\frac{{\mathrm{u}}^2}{4\mathrm{g}}$

• $\frac{{\mathrm{u}}^2}{3\mathrm{g}}$

• $\frac{{\mathrm{u}}^2}{2\mathrm{g}}$

• $\frac{{\mathrm{u}}^2}{\mathrm{g}}$

In the given diagram, if PQ = A, QR = B and RS = C, then PS equals

• A − B + C

• A + B − C

• A + B + C

• A − B − C