2020 - JAMB Physics Past Questions and Answers - page 1
A few grains of table salt were put in a cup of cold water, kept at constant temperature and left undistributed. Eventually all the water tested salty. This action is due to?
convection
osmosis
capillarity
diffusion
Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.
The force required to make an object of mass m, travelling with velocity v, turn in a circle of radius r is
\(\frac{mv^2}{r}\)
\(\frac{mr^2}{x}\)
\(\frac{mr}{v}\)
\(\frac{mv}{r^2}\)
A machine gun with a mass of 5kg fires a 50g bullet at a speed of 100 ms\(^{-1}\). The recoil speed of the machine gun is
0.5 ms\(^{-1}\)
1.5 ms\(^{-1}\)
1 ms\(^{-1}\)
2ms\(^-1\)
Gun momentum = bullet momentum
M\(_a\)V\(_a\) = M\(_b\)V\(_b\)
5 x V\(_a\) = 0.05 x 100
V\(_a\) = 1m\(^{-1}\)
If in a simple pendulum experiment the length of the inextensible string is increased by a factor or four, its period is increased by a factor of?
4
\(\frac{\pi}{2}\)
\(\frac{1}{4}\)
2
For a simple pendulum, T = 2\(\pi\)\(\sqrt{\frac{L}{g}}\)
\(\frac{T_1}{T_2} = \sqrt{\frac{L_1}{L_2}}\) but L\(_2\) = 4L\(_1\)
\(\frac{T_1}{T_2} = \sqrt{\frac{L_1}{4L_1}}\)
T\(_2\) = 2T\(_1\)
In what range of temperature is the expansion of water anomalous?
+208\(^o\)C to +212\(^o\)C
-80\(^o\)C + -76\(^o\)C
0\(^o\)C to +4\(^o\)C
-4\(^o\)C to +0\(^o\)C
The anomalous expansion of water is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 0\(^o\)C to +4\(^o\)C, and it becomes less dense
Which of the following statements about radioactivity is true?
(i) Alpha particle is positively charged
(ii) Beta particle is negatively charged
(iii) Gamma ray is neutral
(iv) Beta particle has the same mass as helium atom
(v) Gamma ray is charged.
i, ii, iii, iv only
i, ii, iii only
iv and v only
i, ii and v only
In the study of Physics, temperature and heat are often confused with each other. Which of the following statements correctly defines these two elements?
Temperature is a measure of the average kinetic energy of the molecules of a substance
Heat is a measure of the total kinetic energy of the molecules in a system
Different materials require different amounts of heat to cause a given change in temperature
All of the above
The effect of closing the key K in the circuit shown in the figure above would be to?
increase the current by 0.4A
reduce the current by 0.4A
increase the current by 0.6A
reduce the current by 0.6A
When K is open, the total Resistance = 8 + 2 = 10\(\Omega\)
1 = \(\frac{V}{\Omega}\) = \(\frac{6v}{\Omega}\) = 0.6A
When K is closed, \(\frac{1}{8} + \frac{1}{8} = \frac{1}{\Omega}\)
\(\frac{2}{8} = \frac{1}{\Omega}\)
\(\Omega\) = \(\frac{8}{2}\) = 4\(\Omega\)
\(\Omega\) = \(\frac{8}{2}\) = 4\(\Omega\)
4\(\Omega\) in series with 2\(\Omega\)= 6\(\Omega\)
1 = \(\frac{V}{\Omega}\) = \(\frac{6}{6}\) = 1A
1 - 0.6A = 0.4A
Hence, 0.4A increase
Which of the following statements on the use of X-rays is incorrect? X-rays are used
In a hospital to obtain photographs of tissues and bones in the body
For the treatment of malignant growths like cancer cells
In detecting fingerprints
To reveal hidden flaws in metal castings and welded joints work of art
Under which of the following conditions is work done?
A boy pushes unto a table
A stands on a table
A man supports a heavy food above his head with his hands
A woman holds a pot of water