JAMB Physics Past Questions & Answers - Page 167

831.

A piece of brass of mass 170kg has its temperature raised from 0oC to 30oC. Calculate its increase in volume, given the density of brass at 0oC as 8.5 x 103kgm3 and its cubic expansivity as 5.7 x 10-1k1

A.

3.4 x 10-5m3

B.

4.3 x 10-5m3

C.

3.4 x 10-5m3

D.

3.4 x 10-3m3

E.

3.4 x 10-2m3

Correct answer is C

V = \(\frac{m}{p}= \frac{170}{8.5 x 10^{-3}}\) = 0.02

= \(\Delta\)\(\frac{\delta V}{V \delta T}\)

\(\delta V\) = \(\Delta\) x V x \(\delta\)T

= 5.7 x 10-5 x 0,02 x 30

= 0 3.42 x 10-5

832.

A ball of mass 5.0kg hits a smooth vertical wall normally with a speed of 2m-1 and rebounds with the same speed. Determine the impulse experienced by the ball

A.

20.0kgm-1

B.

5.0kgm-1

C.

1.3kgm-1

D.

0.0kgm-1

E.

10.0kgm-1

Correct answer is A

No explanation has been provided for this answer.

833.

An object is projected with a velocity of 100m-1 at an angle of 60° to the vertical. Calculate the time taken by the object to reach the highest point (Take g as 10ms-2

A.

5.0s

B.

8.7s

C.

10.0s

D.

17.3s

E.

20.0s

Correct answer is B

t = \(\frac{T}{2} = \frac{1}{2} = \frac{2u \sin \theta}{g} = \frac{100 \times \sin 60}{10}\)

10 sin60 = 10 x 0.8660

= 8.7

834.

A rectangular block of wood floats in water with two-thirds of its volume immersed. When placed in another liquid, it floats with half of its volume immersed. Calculate the relative density of the liquid

A.

1.43

B.

1.33

C.

1.00

D.

0.83

E.

0.75

Correct answer is B

from the first statement, mg = \(\frac{2}{3}Vp_wg\) ........................1

from second statement, mg = \(\frac{1}{2}Vp_lg \)...................2

equating equations 1 and 2    we have that 

\(\frac{2}{3}Vp_wg\) = \(\frac{1}{2}Vp_lg\)

\(\frac{4}{3} = \frac{p_l}{p_w}\)

= 1.33

835.

The term torque means

A.

the moment

B.

the resultant of several forces acting on a body in equilibrium

C.

two equal and oposite forces whose lines of action do not coincide

D.

two coplaner forces at right angles to each other

E.

the equilibrant of two concurrent forces

Correct answer is A

No explanation has been provided for this answer.