2018 - WAEC Physics Past Questions and Answers - page 2

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 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 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 of the absolute scale of temperature is 0 Kelvin, which is -273°C.

The rate of evaporation is increased by the lowering of atmospheric pressure.

10 complete oscillations = 8.0s

1 complete oscillation (period) = \(\frac{8}{10}\)s

Frequency = \(\frac{1}{period}\) = \(\frac{1}{0.8} = 1.25Hz\)

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

The unit of frequency is hertz, abbreviated Hz.

The gamma rays have the shortest wavelength and consequently impart the highest photon energy.