WAEC Physics Past Questions & Answers - Page 154

766.

A block of volume 3 x 105m3 and density 2.5 x 103 kg m-3 is suspended from a spring balance with \(\frac{2}{3}\) of its volume immersed in a liquid of density 900 kg m-3. Determine the reading of the spring balance [g = 10ms-2]

A.

0.18N

B.

0.57N

C.

0.75n

D.

0.93N

Correct answer is B

Volume immersed solid = 3 x 105 x \(\frac{2}{3}\)

= 2 x 105m3

Mass of liquid displaced = ev

= 2 x 105 x 900 = 18 x 107 kg

Upthrust = 18 x 107 x 10

= 7.8 x 109N

Mass of solid = ev

= 2.5 x 103 x 105

= 7.5 x 108

Weight of solid = 7.5 x 108 x10 = 7.8 x 109

Reading = 0.75 - 0.18 = 0.57N

767.

Which of the following physical quantities are derived?

i. Area
ii. Thrust
iii. Pressure
iv. Mass

A.

i, ii, iii and iv

B.

i, ii and iii only

C.

i, ii and iv only

D.

i and iii only

Correct answer is B

No explanation has been provided for this answer.

768.

Which of the following phenomena causes capillary of liquids in tubes of narrow bore?

A.

viscosity

B.

surface tension

C.

osmosis

D.

brownian motion

Correct answer is B

No explanation has been provided for this answer.