JAMB Physics Past Questions & Answers - Page 306

1,526.

A pipe of length 45cm is closed at the end. Calculate the fundamental frequency of the sound wave generated in the pipe if the velocity of sound in air is 360ms-1 [Neglect end correction]

A.

5.5Hz

B.

148.5Hz

C.

200.0Hz

D.

550.0Hz

Correct answer is C

\(\lambda\) = 4L = 4 X 45 = 180cm

F = \(\frac {V}{\lambda}\)

= \(\frac {360}{180 \times 10^{-2}}\)

= 200Hz

1,527.

The fundamental frequency of vibration of a sonometer wire may be halved by

A.

doubling the length of the wire

B.

doubling the mass of the wire

C.

reducing the tension by half

D.

reducing the absolute temperature by half

Correct answer is A

F \(\alpha\) \(\frac{1}{L}\)

1,528.

The sound from a source travelled to the bottom of the sea and the echo was heard 4s later. If the speed of sound in sea water is 1500ms-1 the depth of the sea is

A.

6000m

B.

3000m

C.

1500m

D.

375m

Correct answer is B

t = 4s ; v = 150ms-1

depth = X ; but 2X = vt

X = \(\frac {vt}{2}\) = \(\frac {1500 \times 4}{2}\)

X = 3000m

1,530.

Two similar kettles containing equal masses of boiling water are placed on a table. If the surface of one is highly polished and the surface of the other is covered with soot, Which of the following observations is correct

A.

The two kettles will cool down at the same rate

B.

the polished kettle cools down more quickly by conduction

C.

the kettle covered with soot cools down more quickly because it is a good radiator

D.

the kettle covered with soot cools down more quickly by the process of heat convection

Correct answer is C

No explanation has been provided for this answer.