JAMB Physics Past Questions & Answers - Page 276

1,376.
1,377.

The pressure of a gas when cooled at constant volume will decrease because the molecules

A.

collide less frequently with the walls of the container

B.

have the same average kinetic energy

C.

break up into smaller molecules

D.

decrease in number

Correct answer is A

No explanation has been provided for this answer.

1,378.

A bar of initial length /0 is heated through a temperature change \(\Delta\)t to a new length I. The linear expansivity, a, of the bar is

A.

\(\frac{/ - /_o}{/ \Delta t}\)

B.

\(\frac{/ - /_o}{/_o \Delta t}\)

C.

/o(1 + \(\Delta\) t)

D.

\(\frac{/ - /_o}{/(1 + \Delta t)}\)

Correct answer is B

\(\frac{L - L_o}{L_o \Delta t}\)

1,379.

The resistances of platinum wire at the ice and steam points are 0.75 ohm and 1.05 ohm respectively. Determine the temperature at which the resistance of the wire is 0.90 ohm

A.

43.0oC

B.

50.0oC

C.

69.9oC

D.

87.0oC

Correct answer is B

100oC .... 1.05\(\theta\)

\(\theta\)oC .... 0.9\(\theta\)

0oC .... 0.75\(\theta\)

\(\frac{\theta - 0}{100 - 0}\) = \(\frac{0.9 - 0.75}{1.05 - 0.75}\)

\(\theta\) = 50oC

1,380.

40m3 of liquid is mixed with 60m3 of another liquid Q. If the density of P and Q are 1.00kgm-3 and 1.6kgm-3 respectively, what is the density of the mixture?

A.

0.05kgm-3

B.

1.25kgm-3

C.

1.30kgm-3

D.

1.36kgm-3

Correct answer is D

Mp = 1 x 40 = 40kg ; mQ = 1.6 x 60 = 96kg

volume of mixture = 40 + 60 = 100m3

mass of mixture = 40 + 96 = 136kg

density of mixture = \(\frac{136}{100}\)

= 1.36kgm3