If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

17.

A cell of emf 2 V has an internal resistance of 0.5 Ω. A current of 0.4 A passes through an external resistor, P. Determine the resistance of P.

A.

4.5Ω

B.

C.

D.

E = 2V, r = 0.5Ω, I = 0.4A, P = ?

E = I( R + r )

R = $$\frac{ E}{I} - r$$

R =  $$\frac{ 2}{0.4} - 0.5$$

R = 5 - 0.5 = 4.5Ω

18.

When a light-weight body and a massive body are acted upon by the same force for the same period of time, the

A.

massive body has a higher momentum.

B.

massive body builds up a higher velocity.

C.

lighter body has a higher momentum.

D.

momenta of both bodies remain the same.

When a lightweight body and a massive body are acted upon by the same force for the same time, the momenta of both bodies remain the same.

Given that the momenta of both the heavy and light bodies are the same, it follows that the light body possesses a higher velocity compared to the heavy body.

19.

The specific latent heat of vapourization of lead is 8.7 × $$10^5 Jkg_1$$. This means that 8.7 × $$10^5$$ J of thermal energy is required to change

A.

a given mass of molten lead to vapour at constant temperature and pressure.

B.

1 kg of molten lead to vapour at constant temperature and pressure.

C.

1 kg of solid lead to vapour at constant temperature and pressure.

D.

1 kg of molten lead to vapour for every degree rise in temperature.

The specific latent heat of vaporization of lead is the amount of thermal energy required to change 1 kg of molten lead to vapor at constant temperature and pressure.

20.

A liquid is left in an open dish. After several days, there is less liquid in the dish. Which of the following statements explains this observation? The

A.

most energetic molecules leave the surface and escape into the air.

B.

least energetic molecules leave the surface and escape into air.

C.

most energetic molecules leave the surface and return.

D.

least energetic molecules leave the surface and return.