JAMB Physics Past Questions & Answers - Page 217

1,081.

The electrochemical equivalent of a metal is 0.126 x 10-6 kgC-1. The mass of the metal that a current of 5A will deposit from a suitable bath in 1 hour is

A.

0.0378 x 10 -3kg

B.

0.227 x 10 -3kg

C.

0.378 x 10 -3kg

D.

0.595 x 10 -3kg

E.

2.268 x 10 -3kg

Correct answer is E

m = Itz

= 5 x 3600 x 0.126 x 10-6

= 2.268 x 10-3kg

1,083.

The linear expansivity of brass is 2 x 10-5 oC-1. If the volume of a piece of brass is 10cm3 at 0oC, what will be its volume at 100oC?

A.

10.02cm3

B.

10.04cm3

C.

10.06cm3

D.

10.20cm3

E.

102.00cm3

Correct answer is C

3 x \(\alpha\) = \(\frac{V_2 - V_1}{\Delta \theta \times V_1}\)

3 x 2 x 10-5 = \(\frac{V_2 - 10}{10 \times 100}\)

V2 = 10.06cm3

1,084.

A man of mass 50kg ascends a flight of stairs 5m high in 5 seconds. If acceleration due to gravity is 10ms-2, the power expended is?

A.

100W

B.

200W

C.

250W

D.

400W

E.

500W

Correct answer is E

Power = \(\frac{\text{force x distance}}{\text{time}}\)

= \(\frac{50 × 10 × 5}{5}\)= 500W