WAEC Physics Past Questions & Answers - Page 141

701.

A cube made of metal of linear expansivity \(\alpha\) is heated through a temperature \(\theta\). If the initial volume of the cube is Vo, the correct expression for the increase in volume of the cube is

A.

\(\frac{1}{3} \alpha V_o \theta\)

B.

\(\frac{1}{2} \alpha V_o \theta\)

C.

\(2 \alpha V_o \theta\)

D.

\(3 \alpha V_o \theta\)

Correct answer is D

No explanation has been provided for this answer.

703.

The ice and steam point on a mercury-in-glass thermometer are 10cm and 30cm respectively. Calculate the temperature in degree Celsius when the mercury meniscus is the 14cm mark

A.

20oC

B.

30oC

C.

34oC

D.

70oC

Correct answer is A

\(\frac{x - 0}{100 - 0} = \frac{14 - 10}{30 - 10}\)

x = \(\frac{100 \times 4}{20} = 20^oC\)

704.

Mechanical energy can be either

A.

kinetic or electric

B.

chemical or potential

C.

potential or kinetic

D.

electric or heat

Correct answer is C

No explanation has been provided for this answer.

705.

A plane inclined at 30o to the horizontal has an efficiency of 50%. Calculate the force parallel to the plane required to push a load of 120N uniformly upon the plane

A.

50.0N

B.

120.0N

C.

200.0N

D.

240N

Correct answer is B

V.R = \(\frac{1}{sin\theta} = \frac{1}{sin 30} = 2\)

M.A = \(\frac{E \times V.R}{100} = \frac{50 \times 2}{100} = 1\)

Effort = \(\frac{load}{M.A} = \frac{120}{1} = 120N\)