2009 - JAMB Physics Past Questions and Answers - page 4
31
An object of mass 80 kg is pulled on a horizontal rough ground by a force of 500 N. Find the coefficient of static friction.
[g = 10 ms-2]
[g = 10 ms-2]
A
0.8
B
0.4
C
1.0
D
0.6
correct option: d
coefficient of friction = (F)/R = (F)/ mg = (500)/80 x 10
= 0.625
Users' Answers & Comments= 0.625
32
If a heavy barrel is rolled up a plane inclined at 30° to the horizontal. its velocity ratio will be
A
3.0
B
3.1
C
3.2
D
2.0
33
I. Density of the liquid.
II. Acceleration due to gravity.
III. Type of container of the liquid.
IV. The constituents of the liquid.
which of the above conditions will NOT affect the pressure of fluid?
II. Acceleration due to gravity.
III. Type of container of the liquid.
IV. The constituents of the liquid.
which of the above conditions will NOT affect the pressure of fluid?
A
I and III only
B
II and III only
C
III and IV only
D
I and II only
correct option: c
pressure in fluid is given by P = hlg.
∴ fluid pressure depends on height of liquid column, h, density of liquid p and acceleration of free fall 8. it is therefore independent of type of container and constituents of the liquid
Users' Answers & Comments∴ fluid pressure depends on height of liquid column, h, density of liquid p and acceleration of free fall 8. it is therefore independent of type of container and constituents of the liquid
34
If a load of mass 10N stretched a cord by 1.2cm, what is the total work done?
A
6.0 x 10-2J
B
7.6 x 10-2J
C
1.8 x 10-2J
D
6.6 x 10-2J
correct option: a
Work done on a stretched cord
= Average force x extension
= (10 + 0)/2 x 1.2 x 10-2
= 6.0 x 10-2J
Users' Answers & Comments= Average force x extension
= (10 + 0)/2 x 1.2 x 10-2
= 6.0 x 10-2J
35
A plastic sphere floats in water with 50% of its volume submerged. if it floats in glycerine with 40% of its volume submerged,the density of the glycerine is?
A
1400 kgm-3
B
1250 kgm-3
C
500 kgm-3
D
1000 kgm-3
correct option: b
Weight of glycerine displaced = weight of water dispalced
Mgh glycerine = Mgh water
Pvgh glycerine = Pvgh water
0.4V P glycerine = (0.5v)/v.4v P water = 1.25
(Polycerine)/p water =
But density of substance = relative density x density of water = 1. 25 x 1000kgm3 = 1250kgm-3
Users' Answers & CommentsMgh glycerine = Mgh water
Pvgh glycerine = Pvgh water
0.4V P glycerine = (0.5v)/v.4v P water = 1.25
(Polycerine)/p water =
But density of substance = relative density x density of water = 1. 25 x 1000kgm3 = 1250kgm-3
36
The thermometer whose reading is indicated by a change in colour of its thermometric property is the?
A
bi-metalic strip thermometer
B
thermocouple
C
platinium resistance thermometer
D
optical pyrometer
correct option: d
A pyrometer is instrument for measuring high temperature.
The optical pyrometer is one in which the luminous radiation from the hot body is compared with that from a known source.
Users' Answers & CommentsThe optical pyrometer is one in which the luminous radiation from the hot body is compared with that from a known source.
37
At 4°c, the volume of a fixed mass of water is?
A
constant
B
minimum
C
maximum
D
zero
correct option: b
Anomalous expansion of water is at temperature ranges 0°c to 4°c u. water contract when heated from 0°c to 4°c. thus the volume of water is least at 4°c
Users' Answers & Comments38
An electric heater rated 220v, 1000 w is immersed into a bucket full of water, calculate the mass of water if the temperature changes from 30°c to 100°c and the current flows for 300seconds.
[specific heat capacity of water = 4200 jkg-1 K-1]
[specific heat capacity of water = 4200 jkg-1 K-1]
A
4.28 kg
B
42.86 kg
C
1.02 kg
D
7.14 kg
correct option: c
Energy supplied bythe heater = heater gained by water
pt = MCAθ
1000 x 300 = m x 4200(100 - 30)
m = (1000 x 300)/4200 x 70 = 1.02 kg
Users' Answers & Commentspt = MCAθ
1000 x 300 = m x 4200(100 - 30)
m = (1000 x 300)/4200 x 70 = 1.02 kg
39
If the pressure of the vapour on top of an enclosed liquid is equal to the atmospheric pressure, what will be the temperature of the liquid enclosed?
A
room temperature
B
boiling point
C
freezing point
D
standard temperature
correct option: b
Liquid boils when its sup. is equal to the atmospheric pressure.
Users' Answers & Comments40
A heating coil rated 1000 W is used to boil off completely 2 kg of boiling water. the time required to boil of the water is_______
[Special latent heat of Vaporization of water = 2.3 x 106 Jkg-1]
[Special latent heat of Vaporization of water = 2.3 x 106 Jkg-1]
A
1.15 x 104s
B
1.15 x 103s
C
4.6 x 104s
D
4.6 x 103s
correct option: d
Heat supplied = Heat gained
pt = ml
T = (ml)/p = (2 x 2.3 x 106)/1000 = 4.6 x 103 sec
Users' Answers & Commentspt = ml
T = (ml)/p = (2 x 2.3 x 106)/1000 = 4.6 x 103 sec