# AFCAT: Physics MCQs (Practice_Test 7 of 35)

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If a body of mass m (m is the mass in motion) is moving with a velocity u, then the kinetic energy of the body of rest mass m0 will be

(½) mu2

m0c2

(½) (mc2 − m0u2)

(m-m0) c2

A particle moving with simple harmonic motion through points P and Q with the same velocity. Having taken two seconds in passing from P to Q, it returns to Q after another 2 seconds. The period in seconds is

2

4

6

8

Two harmonic vibrations X = a sin (wt + f) and Y = b sin (wt) represent the displacement of a particle along X and Y axis, respectively. If the phase difference f p =/2, then the trajectory of the particle will be a/an

ellipse

straight line with positive slope

straight line with negative slope

circle

It is possible to distinguish between transverse and longitudinal waves by studying their

reflection

polarisation

diffraction

interference

Which one of the following equations represents a stationary wave?

Y = 2a sin (2p t/T) cos 2p (x/l)

Y = a sin 2 pn (t-x/) l

Y = a sin wt

Y = a sin2 { (t/T) - (x/}) l

A tuning fork ‘X’ of unknown frequency when sounded together with another tuning fork ‘Y’ of frequency 480 Hz gives 4 beats per second. When it is loaded with wax, if it still gives 4 beats/sec, then the frequency of the tuning fork ‘X’ is

476 Hz

480 Hz

484 Hz

486 Hz

The equations yl = al sin w1t and y2 = a2 sin w2t represent two waves. If w1 − w2 is small, then the amplitude of the beats heard will vary from

zero to a1 + a2

zero to a1 − a2

(al-a2)/2 to (al + a2)/2

al-a2 to al + a2

An engine blowing its whistle at a frequency of 1200 Hz approaches a stationary observer with a velocity of 50 ms-1. If the speed of sound is 350 ms-1, then the apparent frequency as heard by the observer is

1400 Hz

1200 Hz

1050 Hz

600 Hz

The angular frequency of motion whose equation is 4 (d2y/dt2) + 9y = 0 is (y is displacement and t = time)

9/4

4/9

3/2

⅔

With symbols having the usual meanings, which one of the following expressions correctly represents forced oscillation?

(d2y/dt2) + w2y = 0

d2y/dt2 = 0

d2y/dt2 + 2k (dy/dt) + w2y = 0

d2y/dt2 + 2k (dy/dt) + w2y = F sin pt

Acoustic grating is obtained by

ruling a glass plate

ruling a cellulose plate

sending ultrasonics through a fluid

ruling a plastic sheet

If there is no transmission of energy in the medium, then the propagated wave is a/an

electromagnetic wave

longitudinal wave

transverse wave

stationary wave

Which one of the following vibrating systems can oscillate under resonance?

Two pendulums of equal length suspended from a rigid support

Two pendulums of equal length suspended from a flexible support

Two pendulums of unequal length suspended from a rigid support

Two pendulums of unequal lengths suspended from a flexible support

Match List I with List II and select the correct answer

List-I (Microphone) List-II (Principle) Capacitor microphone

Crystal microphone

Carbon microphone

Ribbon microphone

Change in resistance

Induced emf

Change in voltage

Change in electrical energy

- A
- B
- C
- D

- 4
- 3
- 2
- 1

- 3
- 4
- 2
- 1

- 3
- 4
- 1
- 2

- 4
- 3
- 1
- 2

Match List I with List II and select the correct answer

List-I List-II Velocity of sound in air

Analysis of complex sound

Frequency of a fork

Young's modulus of a rod

Kundt's tube

Sonometer

Helmholtz resonator

Resonance column apparatus

- A
- B
- C
- D

- 4
- 3
- 2
- 1

- 4
- 3
- 1
- 2

- 3
- 4
- 2
- 1

- 3
- 4
- 1
- 2