SECTION-B

Two bodies having equal masses are moving with a uniform speed of $v$ and $2v$, respectively. Find the ratio of their kinetic energies.

 Name four ways in which sound can be produced.

Calculate the speed of a sound wave whose frequency is $2 \mathrm{kHz}$, and wavelength $65 \mathrm{c}\mathrm{m}.$

 Write the three equations of uniformly accelerated motion. Give the meaning of each symbol that occurs in them.

If a balloon filled with air and its mouth untied, is released with its mouth in the downward direction, it moves upwards. Why?

An unloaded truck weighing $2000 \mathrm{k}\mathrm{g}$ has a maximum acceleration of $0.5 \mathrm{m} {\mathrm{s}}^{-2}$. What is the maximum acceleration when it is carrying a load of $2000 \mathrm{k}\mathrm{g}$? 

A body is moving uniformly in a straight line with a velocity of $5 \mathrm{m}/\mathrm{s}$. Find graphically the distance covered by it in $5$ seconds.

A moving bicycle comes to rest after sometime if we stop pedalling it. But Newton's first law of motion says that a moving body should continue to move forever, unless some external force acts on it. How do you explain the bicycle case?