# 2011 - JAMB Physics Past Questions and Answers - page 1

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

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

Users' Answers & CommentsMg - 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 ms

^{1}.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

v

0 = 100

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.

Users' Answers & Comments^{2}= U^{2}- 2G s0 = 100

^{2}- 2 x 10 x s = 10000 - 20ss = (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

4

An object of mass 2 kg moves with a velocity of 10 ms

^{1}round at circle of radius 4 m. Calculate the centripetal force on the objectA

25 N

B

100 N

C

50 N

D

40 N

**correct option:**c

Centripetal force,

F = \( \frac{mv^2}{r} \)

= \( \frac{2 \times 10^2}{4} \)

= \( \frac{200}{4} \)= 50N

Users' Answers & CommentsF = \( \frac{mv^2}{r} \)

= \( \frac{2 \times 10^2}{4} \)

= \( \frac{200}{4} \)= 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

[g = 10 ms

^{-2}]A

600 J

B

150J

C

300 J

D

450 J

**correct option:**c

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

Users' Answers & Comments= 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

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

Users' Answers & Comments7

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

[g = 10 ms

[g = 10 ms

^{2}]A

50 N

B

520 N

C

220 N

D

80 N

**correct option:**d

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

Users' Answers & Comments8

A metal of volume 40 cm

^{3}is heated from 30 °c to 90 °c, the increase in volume isA

0.12 cm

^{3}B

4.00 cm

^{3}C

1.20 cm

^{3}D

0.40 cm

^{3}**correct option:**e

Correct Answer: Option E
increase in volume, DV = RV

Users' Answers & Comments_{1}∆ θ = 3α Vsub>19

A copper wire was subjected to a tensile stress of 7.7 x 10

[young modules = 1.1 x 10

^{7}x 10 Nm^{-2}. calculate strain of the wire.[young modules = 1.1 x 10

^{11}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

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} \)

Users' Answers & Comments= \( 1.1 \times 10^11 = \frac{7.7 \times 10^7}{\text{Tensile Strain}} \)

∴ 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.

III.Easy readability.

IV. Accuracy over a wide range of temperature

From the statement above, the qualities of a good thermometer are

II. High sensitivity.

III.Easy readability.

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

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

Users' Answers & Comments∴ II, III and IV are qualities of a good thermometer