JAMB Physics Past Questions & Answers - Page 444

2,216.

I. Temperature.
II. Density of air molecules
III. Pressure
IV. Pitch
Which of the above will affect the velocity of sound in the air

A.

I and II only

B.

II and IV only

C.

I,II and IV only

D.

I,II,III and IV

Correct answer is A

Air pressure has no effect on speed of sound in an ideal gas because pressure and density both contribute to sound velocity equally, the two effects cancel each other out

2,217.

The radiator of a motor car is cooled by

A.

radiation

B.

conduction

C.

convection

D.

radiation and conduction

Correct answer is C

The function of the radiator of a motor car is to "collect" heat from the circulating water and radiate some out, but it is itself cooled by the fan adjacent to it. whose function is primarily based on convection

2,218.

A coin place below a rectangular glass block of thickness 9cm and refractive index 1.5 is viewed vertically above the block. The apparent displacement of the coin is

A.

3 cm

B.

5 cm

C.

6 cm

D.

8 cm

Correct answer is A

Real depth = thickness of the glass block = 9cm.
Refractive index of the glass material = 1.5
But Refractive index = Real depth/Apparent depth
=> 1.5 = 9/Apparent depth
therefore Apparent depth = 9/1.5 = 6cm.
therefore Apparent displacement of the Coin = 9.6
= 3cm

2,219.

The effect of a particle in a fluid attaining its terminal velocity is that the

A.

acceleration is maximum

B.

weight is equal to the retarding force

C.

buoyancy force is equal to the to the viscous retardind force

D.

buoyancy force is more than the weight of the fluid displaced

Correct answer is B

No explanation has been provided for this answer.

2,220.

A particle in circular motion performs 30 oscillation in 6 seconds. Its angular velocity is

A.

5 rad s-1

B.

6 rad s-1

C.

5π rad s-1

D.

10π rad s-1

Correct answer is D

Angular velocity w = 2π f.
But f = frequency no. of oscillations per second.
= 30/6 = 5Hz.
therefore W = 2π x 5
= 10π rad. s-1