WAEC Physics Past Questions & Answers - Page 172

856.

An elastic string of force constant 200N m-1 is stretched through 0.8m within its elastic limit. Calculate the energy stored in the string

A.

64.0J

B.

80.0J

C.

128.0J

D.

160.0J

Correct answer is A

E = \(\frac{1}{2}Ke^2\)

= \(\frac{1}{2} \times 200(0.8)^2 = 64J\)

857.

On which of the following factors does the viscosity of a liquid depend?

i. Nature of the liquid.
ii. Temperature of the liquid.
iii. Area of the liquid surface

A.

i and ii only

B.

ii and iii only

C.

i and iii only

D.

i, ii and iii

Correct answer is D

No explanation has been provided for this answer.

858.

A steel needle floating on water, sinks when kerosine is added to the water. This is because the kerosine

A.

increased the surface tension of the water

B.

reduces the density of the water

C.

reduces the surface tension of the water

D.

reduces the upthrust on the needle

Correct answer is C

No explanation has been provided for this answer.

859.

A diver is 5.2m below the surface of water of density 1000Kgm-3. If the atmospheric pressure is 1.02 x 105pa. Calculate the pressure on the diver [g = 10ms-2]

A.

6.20 x 104 pa

B.

1.02 x 105 pa

C.

1.54 x 105 pa

D.

5.20 x 105 pa

Correct answer is C

P = hpg + A.P

= 5.2 x 1000 x 10 + 1.02 x 105

= 1.54 x 105

860.

Which of the following concept is not an evidence of the particle nature of matter?

A.

diffusion

B.

brownian motion

C.

diffraction

D.

crystallization

Correct answer is D

No explanation has been provided for this answer.