Waec Physics 2017 Past Questions and Answers

Question 21:

• WAEC 2017

A motor of a corn mill machine operates on electrical energy of \(1.44 \times 10^{5}\)J. If one-quarter of the energy is wasted on sound and heat, determine the efficiency of the machine.

A. 25%
B. 36%
C. 64%
D. 75%

Question 22:

• WAEC 2017

Thermal energy added or removed from a substance that changes the state of the substance is called

A. Latent heat
B. Heat of reaction
C. Calorimetry
D. Specific heat

Question 23:

• WAEC 2017

The maximum density of water occurs at a temperature of

A. 0°C
B. 4°C
C. 37°C
D. 273°C

Question 24:

• WAEC 2017

A vapour whose molecules are in dynamic equilibrium with those of its own liquid is said to be

A. Unsaturated
B. Gaseous
C. Saturated
D. Diffused

Question 25:

• WAEC 2017

The diagram above illustrates two waves of equal amplitudes A and frequencies approaching each other. When the two waves meet at a point I midway between them, the vertical displacement of the resulting wave will be

B. \(\frac{A}{2}\)
C. \(\frac{A}{4}\)
D. \(2A\)