# 2011 JAMB Physics Past Questions & Answers - page 1

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1
A man standing on a lift that is descending does not feel any weight because
A the inside of the lift is air tight
B the lift is in vacuum
C there is no reaction from the floor of the lift
D there is no gravitational pull on the man in the lift

Correct Option: C

Solution
The resultant force acting on the man is given by w = mg - R
Mg - mg = 0
The man feels weightless because the reaction, R is equal to the weight mg

2
Two balls X and Y weighing 5 g and 50 kg respectively were throne up vertically at the same time with a velocity of 100 ms1 .How will their positions be one second later?
A X and Y will be 500 m from each other
B Y will be 500 m ahead of X
C X will be 500 m ahead of Y
D X and Y both be 500 m from the poin of throw

Correct Option: D

Solution
v2 = U2 - 2G s
0 = 1002 - 2 x 10 x s = 10000 - 20s
s = (10000)/20 = 500m
Which is independent of mass.the two bodies where acted upon by the same retarding force of gravity which is independent of mass of the body; therefore both will be 500 m from the point of throw.

3
If it takes an object 3s to fall freely to the ground from a certain height, what is the distance covered by the object?
A 90 m
B 30 m
C 45 m
D 60 m

Correct Option: C

Solution
S = (1)/2gt2
S = (1)/2 x (10)/1 x 32 =5 x 9 = 45 m

4
An object of mass 2 kg moves with a velocity of 10 ms1 round at circle of radius 4 m. Calculate the centripetal force on the object
A 25 N
B 100 N
C 50 N
D 40 N

Correct Option: C

Solution
Centripetal force,
F = $$\frac{mv^2}{r}$$
= $$\frac{2 \times 10^2}{4}$$
= $$\frac{200}{4}$$= 50N

5
A carpenter on top of a roof of 20.0m high dropped a hammer of mass 1.5 kg and it fell directly to the ground. the kinetic energy of the hammer just before hitting the ground is?

[g = 10 ms-2]
A 600 J
B 150J
C 300 J
D 450 J

Correct Option: C

Solution
K e just before hitting the gound
= P e at the maximum height (conservation of mechanical energy)
K e = P e = mgh = 1.5 x 10 x 20
= 300 J

6
If a tube of small radius opened at both ends is placed in a liquid, the liquid will
A remain at the same level irrespective of whether the liquid wet the glass or not
B fall below the liquid level if the liquid wets the glass
C falls below the liquid level if the liquid does not wet the glass
D rise above the liquid level if the liquid does not wet the glass

Correct Option: C

Solution
The liquid will rise up the capillary if it wets glass and falls below its wets glass and falls below its initial level if it does not wet glass

7
An object weighs 22 kg in water and 30kg in air. what is the upthrust exerted by the liquid on the object.

[g = 10 ms2]
A 50 N
B 520 N
C 220 N
D 80 N

Correct Option: D

Solution
upthrust = weight in air - weight in liquid = 30 x 10 - 22 x 10 = 300 - 220 = 80 N

8
A metal of volume 40 cm3 is heated from 30 °c to 90 °c, the increase in volume is
A 0.12 cm3
B 4.00 cm3
C 1.20 cm3
D 0.40 cm3

Correct Option: E

Solution
##### Correct Answer: Option E increase in volume, DV = RV1 ∆ θ = 3α Vsub>1

9
A copper wire was subjected to a tensile stress of 7.7 x 107 x 10 Nm-2. calculate strain of the wire.

[young modules = 1.1 x 1011 Nm-2]
A 2. 0 x 10-5
B 7.0 x 10-3
C 7.0 x 10-4
D 2.2 x 10-4

Correct Option: C

Solution
Young modules = $$\frac{\text{Tensile stress}}{\text{Tensile strain}}$$

= $$1.1 \times 10^11 = \frac{7.7 \times 10^7}{\text{Tensile Strain}}$$

∴ Tensile strain = $$\frac{7.7 \times 10^7}{1.1 \times 10^11}$$

= $$7.0 \times 10^{7-11} = 7.0 \times 10^{-4}$$

10
I. High thermal capacity.
II. High sensitivity.
IV. Accuracy over a wide range of temperature
From the statement above, the qualities of a good thermometer are
A I and II
B I, II,III and IV
C I, III and IV
D II, III and IV

Correct Option: D

Solution
A good thermometric liquid should not have a high thermal capacity so that the themperetue of the body being measured will not be affected
∴ II, III and IV are qualities of a good thermometer

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