4
MCQ (Single Correct Answer)
An aluminium sphere is dipped into water. Which of the following is true?
A
Buoyancy will be less in water at $0^{\circ} \mathrm{C}$ than that in water at $4^{\circ} \mathrm{C}$
B
Buoyancy will be more in water at $0^{\circ} \mathrm{C}$ than that in water at $4^{\circ} \mathrm{C}$
C
Buoyancy in water at $0^{\circ} \mathrm{C}$ will be same as that in water at $4^{\circ} \mathrm{C}$
D
Buoyancy may be more or less in water at $4^{\circ} \mathrm{C}$ depending on the radius of the sphere
5
MCQ (Single Correct Answer)
As the temperature is increased, the period of a pendulum
A
increases as its effective length increases even though its centre of mass still remains at the centre of the bob
B
decreases as its effective length increases even though its centre of mass still remains at the centre of the bob
C
increases as its effective length increases due to shifting to centre of mass below the centre of the bob
D
decreases as its effective length remains same but the centre of mass shifts above the centre of the bob
6
MCQ (Single Correct Answer)
Heat is associated with
A
kinetic energy of random motion of molecules
B
kinetic energy of orderly motion of molecules
C
total kinetic energy of random and orderly motion of molecules
D
kinetic energy of random motion in some cases and kinetic energy of orderly motion in other
7
MCQ (Single Correct Answer)
The radius of a metal sphere at room temperature $T$ is $R$ and the coefficient of linear expansion of the metal is $\alpha$. The sphere heated a little by a temperature $\Delta T$ so that its new temperature is $T+\Delta T$. The increase in the volume of the sphere is approximately.
A
$2 \pi R \alpha \Delta T$
B
$\pi R^2 \alpha \Delta T$
C
$4 \pi R^3 \alpha \Delta T / 3$
D
$4 \pi R^3 \alpha \Delta T$
8
MCQ (Single Correct Answer)
A sphere, a cube and a thin circular plate, all of same material and same mass are initially heated to same high temperature.
A
Plate will cool fastest and cube the slowest
B
Sphere will cool fastest and cube the slowest
C
Plate will cool fastest and sphere the slowest
D
Cube will cool fastest and plate the slowest