2018 - WAEC Physics Past Questions and Answers - page 2
An object at rest is said to possess
potential energy
kinetic energy
chemical energy
electrical energy
Potential energy is the energy that is stored in an object due to its position relative to some zero reference position.
According to Newton's law of cooling, the heat energy lost per unit area of a body depends on the
I. Surface area
II. Nature of the surface
III. Temperature of the surface
IV. Excess temperature over the surroundings
I and II only
II and IV only
I,II and III
I, II and IV
According to Newton's law of cooling, the rate of cooling of liduid according to depends on:
- Temperature of the liquid
- Temperature of the enclosure
- The area of the exposed surface
- The nature and extent of the surface of the containing vessel
The graph of density against temperature for water is correctly illustrated by
A football is kicked at an angle of 45° to the horizontal over a defense line up with a velocity of 15\(ms^{-1}\). Calculate the magnitudeof horizontal velocity of the ball at its highest point [Neglect friction, g = 10\(ms^{-2}\)].
0.0\(ms^{-1}\)
5.6\(ms^{-1}\)
10.6\(ms^{-1}\)
15.0\(ms^{-1}\)
The horizontal component of velocity, \(V_{x}\), is unaffected by the acceleration of free fall hence, it remains constant.
\(V_{x} = U_{x} = Ucos\theta\)
= \(15 \times cos45 = 15\times 0.7071\)
\(\approxeq 10.6ms^{-1}\)
The ice point on the absolute scale of temperature is
0K
32K
100K
273K
The ice point of the absolute scale of temperature is 0 Kelvin, which is -273°C.
Which of the following factors does not increase the rate of evaporation of water in a lake?
Increase in the pressure of the atmosphere
Rise in temperature
Increase in the surface area of the lake
Increase in the speed of the wind
The rate of evaporation is increased by the lowering of atmospheric pressure.
The bob of a simple pendulum takes 8.0s to complete 10 oscillations. Determine the frequency of oscillation of the bob.
10 complete oscillations = 8.0s
1 complete oscillation (period) = \(\frac{8}{10}\)s
Frequency = \(\frac{1}{period}\) = \(\frac{1}{0.8} = 1.25Hz\)
The diagram above illustrates the mercury-in-glass thermometer used for determining the temperature of a room. Use the data on it to determine the room temperature.
3.3°C
7.0°C
13°C
30.0°C
Let the room temperature be X.
Then,
\(\frac{3-0}{10-0} = \frac{X-0}{100-0}\)
\(\frac{3}{10} = \frac{X}{100}\)
\(X = \frac{3 \times 100}{10}\)
= 30°C
Frequency is measured in
Which of the following electromagnetic waves is most energetic?
Radio waves
X-ray
Gamma rays
Ultra-violet rays
The gamma rays have the shortest wavelength and consequently impart the highest photon energy.