JAMB Physics Past Questions & Answers - Page 256

1,276.

A body whose mass is 2kg and has a volume of 500cm3 just floats when completely immersed in a liquid. Calculate the density of the liquid

A.

4.0 x 102kgm-3

B.

4.0 x 103kgm-3

C.

1.0 x 103kgm-3

D.

1.0 x 106kgm-3

Correct answer is B

since the object floats, density of liquid = density of object

converting 500cm3 to m3,

\(\frac{500}{10^{6}} = 5 \times 10^{-4}m^{3}\)

D = \(\frac{m}{v}\)

= \(\frac{2}{5 \times 10^{-4}}\)

=\(4.0 \times 10^{3}kgm^{-3}\)

1,277.

A force, 10N, drags a mass 10kg on a horizontal table with an acceleration of 0.2ms. If the acceleration due to gravity is 10ms-1, the coefficient of friction between the moving mass and the table is

A.

0.02

B.

0.08

C.

0.20

D.

0.80

Correct answer is B

\(\mu\)mg = ma

\(\mu\)mg = F - ma

\(\mu\) x 10 x 10 = 10 - (10 x 0.2)

100 \(\mu\) =10 - 2

dividing both sides by 100

\(\mu\) = 8 / 100

\(\mu\) = 0.08

1,278.

How long will it take a 60kg man to climb a height of 22m if he expended energy at a rate of 0.25kW. [g = ms-2]

A.

5.3s

B.

34.5s

C.

41.6s

D.

52.8s

Correct answer is D

power = mgh

0.25 x 103 = \(\frac {60 \times 10 \times 22}{t}\)

t = 52.8 sec

1,279.

A 20-toothed gear wheel drives a 60-toothed one. If the angular speed of the smaller wheel is 120 rev s-1, the angular speed of the larger wheel is

A.

3 rev s-1

B.

40 rev s-1

C.

360 rev s-1

D.

2400 rev s-1

Correct answer is C

\(\frac{\text {speed of driver}}{\text {speeder driven}}\) = \(\frac{\text {no. of teeth of driver}}{\text {no. of teeth of driven}}\)

\(\frac{120}{V}\) = \(\frac{20}{60}\)

v = 360 rev s-1

1,280.

A particle starts from rest and moves with a constant acceleration of 0.5ms-2. The distance covered by the particle in 10s is?

A.

2.5m

B.

5.0m

C.

25.0m

D.

50.0m

Correct answer is C

X = ut + \(\frac{1}{2}\)at

= (0 x 10) + (\(\frac{1}{2}\) x 0.5 x 10 x 10)

= 25m