# Competitive Exams: 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
- () mu2
- m0c2
- () (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)
- 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