JAMB Physics Past Questions & Answers - Page 343

1,711.

A wire of length 100.0m at 30o has linear expansive of 2x10-5K-1 Calculate the length of the wire at a temperature of - 10oC

A.

100.08m

B.

100.04m

C.

99.96m

D.

99.92m

Correct answer is D

\(L_2 = L_1 + \alpha(\theta_2 - \theta_1)\)

= 100 + 0.00002(-10-30) = 99.92

1,712.

What volume of alcohol will have same mass as 4.2m-3 of petrol?
Density of alcohol = 8.4 x 10^2 kgm-3, density of petrol =7.2x10^2 kgm-3

A.

0.8m3

B.

1.4m3

C.

3.6m3

D.

49.m3

Correct answer is C

Mp = ep x Vp

Mp = 7.2 x 102 x 4.2 = 3024

VA = \(\frac{M}{e_A}\)

VA = \(\frac{3024}{8.4 \times 10^2}\)

VA = 3.6

1,713.

Calculate the work done when a force of 20N stretches a spring by 50mm.

A.

0.5J

B.

1.5J

C.

2.0J

D.

2.5J

Correct answer is A

W = \(\frac{1}{2}Fe\)

W = \(\frac{1}{2}\times 20 \times 0.05\)

W = 0.5J

1,714.

If a pump is capable of lifting 5000kg of water through a vertical height of 60m in 15 min, the power of the pump is

A.

2.2.5 x 10 5js-1

B.

2.5 x 104js-1

C.

3.3 x 103js-1

D.

3.3 x 102js-1

Correct answer is C

P = \(\frac{mgh}{t}\)

P = \(\frac{5000 \times 10 \times 60}{(15 \times 60)s}\)

P = 3333.3333

P = 3.3 x 103js-1

1,715.

An object is moving with a velocity of 5m-1. At what height must a similar body be situated to have a potential energy equal in value with kinetic energy of the moving body?

A.

25.0m

B.

20.0m

C.

1.3m

D.

1.0m

Correct answer is C

P.E = K.E

Therefore, h = \(\frac{v^2}{2g} = \frac{5^2}{2 \times 10}\)

= 1.25

Approx 1.3 (C)