Physics Past Questions and Answers

I. A liquid boils when its saturated vapour pressure is equal to the external pressure
II. Dissolved substances in pure water lead to increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decrease the boiling point.
Which combination of the above are peculiarities of the boiling point of a liquid?

The temperature gradient across a copper rod of thickness 0.02m, maintained at two temperature junctions of 20°C and 80°C respectively is

Calculate the mass of ice that would melt when 2kg of copper is quickly transferred from boiling water to a block of ice without heat loss;
Specific heat capacity of copper = 400JKg^-1K^-1
Latent heat of fusion of ice = 3.3 x 10⁵JKg^-1

The equation of a wave travelling along the positive x-direction is given by;
y = 0.25 x 10^-3 sin (500t - 0.025x).
Determine the angular frequency of the wave motion.

If a sound wave goes from a cold air region to a hot air region, its wavelength will