1998 - WAEC Physics Past Questions and Answers - page 2
11
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
correct option: a
Users' Answers & Comments12
An object is heated from 30oC to 57oC. The increases in its temperature on the kelvin scale is
A
17k
B
27k
C
81k
D
246k
13
The lower and upper fixed points of a mecury-in-glass thermometer are marked Y and 180mm respectively. On a particular the mecury meniscus in the thermometer rises to 45mm. If the corresponding reading on a scale is 10o, calculate the value of Y.
A
4mm
B
18mm
C
30mm
D
135mm
correct option: c
Users' Answers & Comments14
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
correct option: 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
Users' Answers & Comments= \(\Delta\)\(\frac{\delta V}{V \delta T}\)
\(\delta V\) = \(\Delta\) x V x \(\delta\)T
= 5.7 x 10-5 x 0,02 x 30
= 0 3.42 x 10-5
15
The average kinetic energy of the molecules of a perfect gas is directly proportional to the
A
pressure exerted by the gas
B
volume of the gas molecule
C
kelvin temperature of the gas
D
volume of the gas container
correct option: e
Users' Answers & Comments16
How much heat is emitted when a body of mass 200g cools from 37oC to 31oC? (specific heat capacity of the body = 0.4Jg-1K-1,)
A
4800J
B
1200J
C
480J
D
202J
17
If the cubic expansivity of brass between 27oC and 100oC is 5.7 x 10-5K-1, What is its linear expansivity?
A
2.85 x 10-5K-1
B
1.90 x 10-5K-1
C
1.86 x 10-5K-1
D
1.70 x 10-5K-1
correct option: b
\(\alpha\) = \(\frac{\Delta}{3} = \frac{5.7 \times 10^{-5}}{3}\)
= 1.90 x 10-5K-1
Users' Answers & Comments= 1.90 x 10-5K-1
18
Air at temperature 527oC and pressure 30 atmospheres is admitted into the cylinder of an engine. Calculate the pressure of the gas when it has expanded to 5 times its volume and cooled to 127oC as it leaves the engine
A
1.5 atmospheres
B
2.5 atmospheres
C
3.0 atmospheres
D
12.8 atmospheres
correct option: c
\(\frac{V_1P_1}{T_1} = \frac{V_2P_2}{T_2}\)
\(\frac{1 \times 30}{527 + 2733} = \frac{5P_2}{127 + 273}\)
\(\frac{30}{800} = \frac{5p_2}{400}\)
P2 = \(\frac{400 \times 30}{800 \times 5}\)
= 3
Users' Answers & Comments\(\frac{1 \times 30}{527 + 2733} = \frac{5P_2}{127 + 273}\)
\(\frac{30}{800} = \frac{5p_2}{400}\)
P2 = \(\frac{400 \times 30}{800 \times 5}\)
= 3
19
The inside of a vacuum flak is usually coated with silver to reduce heat loss by
A
evaporation
B
radiation
C
conduction
D
convention
correct option: b
Users' Answers & Comments20
Dry oxygen is trapped by a pellet of mercury in a uniform capillary tube which is sealed at one end. The length of the column of oxygen at 27oC is 50cm. if the pressure of the oxygen is constant, at what temperature will the length be 60cm?
A
360.0oC
B
240.6oC
C
237.0oC
D
87.0oC
correct option: d
T1 = \(\frac{V_1T_2}{V_2} = \frac{60 \times (273 + 27)}{50}\)
= 360k
= 360 - 273
= 87.0oC
Users' Answers & Comments= 360k
= 360 - 273
= 87.0oC