# 2007 JAMB Physics Past Questions & Answers - page 1

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1
The unit of moment of a couple can be expressed in?

A N m

^{-1}
B N m

^{-2}
C N m

D N m

^{2}**Correct Option:** C

**Solution**

2
A gramophone record takes 5s to reach its constant angular velocity of 4\(\pi\) rads

^{-1}from rest. Find its constant angular acceleration.
A 0.4\(\pi\) rads

^{-2}
B 0.8\(\pi\) rads

^{-2}
C 1.3\(\pi\) rads

^{-2}
D 20.0\(\pi\) rads

^{-2}**Correct Option:** B

**Solution**

V = +at, and if it starts from N & T, U = 0

And for angular motion, W = O + at

4R = aχ5

∴ a = (4a)/5 = 0. 8\(\pi\) rads

^{-2}

3
A car of mass 1500 kg goes round a circular curve of radius 50m at a speed of 40 ms

^{-1}. The magnitude of the centripetal force on the car is ?
A 4.8 x 10

^{4}N
B 4.8 x 10

^{3 }N
C 1.2 x 10

^{3 }N
D 1.2 x 10

^{2}N**Correct Option:** A

**Solution**

^{2}/r

= (1500 x 40 x40)/50

= 48000 = 4.8 x 10

^{4}N

4
Two spheres of masses 5.0 kg and 10.0 kg are 0.3 m apart. Calculate the force of attraction between them?

[G = 6.67 X 10

[G = 6.67 X 10

^{-11}Nm^{2}Kg^{2}]
A 3.50 x 10

^{-10}N
B 3.71 x 10

^{-8}N
C 3.57 x 10

^{-2}N
D 4.00 x 10

^{2}N**Correct Option:** B

**Solution**

_{1}M

_{2})/r

^{2}= (6.67X 10

^{-11}X5X10)/(0.3)

^{2}

= 3.71 X 10

^{-8}N.

5
A machine has a velocity ratio of 4. if it requires 800 N to overcome a load of 1600 N,what is the efficiency of the machine?

A 60%

B 50%

C 40%

D 2%

**Correct Option:** B

**Solution**

But M.A = (Load)/Effort = (1600)/800 = 2

Efficiency = (2)/4 x (100)/1 = 50%

6
A reservoir 500 m deep is filled with a fluid of density 850 kgm

[g = 10ms

^{-3}. If the atmospheric pressure is 1.05 x 10^{5}Nm^{-2}, the pressure at the bottom of the reservoir is.[g = 10ms

^{-2}]
A 4.72 x 10

^{6}Nm^{-2}
B 4.36 x 10

^{6}Nm^{-2}
C 4.28 x 10

^{6}Nm^{-2}
D 4.25 x 10

^{6}Nm^{-2}**Correct Option:** D

**Solution**

= 850 x 10 x 500

= 4250000

= 4.25 x 10

^{6}NM

^{-2}

7
A piece of iron weights 250 N in air and 200 N in a liquid of density 1000 kgm

^{-3}. the volume of the iron is?
A 5.0 x 10

^{-2}ms^{-2}
B 4.5 x 10

^{--2}ms^{-3}
C 2.5 x 10

^{-2}ms^{-8}
D 2.0 x 10

^{-2}ms^{-3}**Correct Option:** C

**Solution**

wt. in the liquid = 200N

loss in wt. in the liquid = 250 - 200 = 50N

∴ Wt. the liquid of equal vol. of the iron = 50N

∴If the density of the liquid is 1000 lgm

^{-3}

then the volume of the liquid = (N)/D = V = (25kg)/1000 =0.025m

^{3}= 2.5 x 10

^{-2}m

^{8}.

8
A clinical thermometer is different from other mercury in glass thermometers owing to

A the constriction on its stem

B the grade of mercury used in it

C its long stem

D its wide range of temperatures

**Correct Option:** A

9
I. Use a liquid with a high melting point.

II. use a liquid of high volume expansivity.

III. use a capillary tube of large diameter.

which of the above best describes how the sensitivity of a liquid-in-glass thermometer can be enhanced?

II. use a liquid of high volume expansivity.

III. use a capillary tube of large diameter.

which of the above best describes how the sensitivity of a liquid-in-glass thermometer can be enhanced?

A I only

B II. only

C I and II only

D II and III only

**Correct Option:** B

**Solution**

10
2 kg of water is heated with a heating coil which draws 3.5 A from a 200 V mains for 2 minutes. what is the increase in temperature of the water?

[specific heat capacity of water = 4200 jkg

[specific heat capacity of water = 4200 jkg

^{-1}k^{-1}]
A 30°

B 25°

C 15°

D 10°

**Correct Option:** D

**Solution**

and this heat is supplied to the 2 kg of the water MC ∆ t = 84000

2 x 4200 x ∆ t = 84000

∴ ∆t = (84000)/8400 = 10°c

∴ increase in temp. of water = 10°c

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