Physics Past Questions and Answers

Question 4726:

A small needle is carefully floated on water in a beaker. When a few drops of kerosene are introduced into the water, the needle sinks. Which of the following statements correctly explains the observation?

I. There is tension on the water surface II. Kerosene reduces the density of water so that the needle becomes denser than water

III. Kerosene reduces the surface tension of water

A. I only
B. II only
C. III only
D. I and. II
E. I and III

Question 4727:

Which of the following is a correct explanation of the inertia of a body?

A. Ability to overcome the earth's gravity
B. Reluctance to stop moving
C. Readiness to start moving
D. Reluctance to start moving and its readiness to stop moving once it has begun to move
E. Reluctance to start moving and its reluctance to stop moving once it has begun to move

Question 4728:

Two masses $40\mathrm{g}$ and $60\mathrm{g}$ are attached firmly to the ends of a light meter rule. The centre of gravity of the system is

A. At the midpoint of the meter rule
B. $40\mathrm{cm}$ from the lighter mass
C. $40\mathrm{cm}$ from the heavier mass
D. $60\mathrm{cm}$ from the heavier mass

Question 4729:

The mode of heat transfer which does not require a material medium is

A. Conduction
B. Radiation
C. Convection
D. Propagation

Question 4730:

When two objects $P$ and arc supplied with the same quantity of heat, the temperature change in $P$ is observed to be twice that of $Q$, the mass of $P$ is half of $Q$, the ratio of the specific heat of $P$ to that of $Q$ is

A. $1:4$
B. $4:1$
C. $1:1$
D. $2:1$