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**NEET Physics Chapter Wise Mock Test – Waves and Oscillations**

**Question 1:
**When an observer moves towards a stationary source with a certain velocity, he observes an apparent frequency f. When it moves away from the source with same velocity, the observed frequency is 0.8 f. If the velocity of sound is v, then the speed of the observer is

(a) V/4

(b) V/8

(c) V/9

(d) None of these

**Question 2:
**A transverse wave y = 0.05 sin (20πx -50π t) in metre, is propagating along positive X-axis on a string. A light insect starts crawling on the string with the velocity of 5 cms

^{-1}at t = 0 along the positive X-axis from a point where x = 5 cm. After 5s the difference in the phase of its position is equal to

(a) 150π

(b) 250π

(C) 10π

(d) 5π

**Question 3:
**Equation of a progressive wave is given by

y =0.2cos π(o.04t+0.02x-π/6)

The distance is expressed in cm and time in second. What will be the minimum distance between two particles having the phase difference of π/2 ?

(a) 4 cm

(b) 8cm

(c) 25cm

(d) 12.5 cm

**Question 4:
**Two waves represented by the following equations are travelling in the same medium

y

_{1}= 5 sin 2π(75t – 0.25x)

y

_{2}= 10 sin 2π(150t – 0.50x)

The intensity ratio l

_{1}/l

_{2}of the two waves is

(a) 1:2

(b) 1: 4

(c) 1:8

(d) 1:16

**Question 5:
**Two sources of sound A and B produces the wave of 350 Hz, in the same phase. The particle P is vibrating under the influence of these two waves, if the amplitudes at the point P produces by the two waves is 0.3 mm and 0.4 mm, then the resultant amplitude of the point P will be when AP -BP =25 cm and the velocity of sound is 350 ms

^{-1}

(a) 0.7 mm

(b) 0.1 mm

(c) 0.2 mm

(d) 0.5 mm

**Question 6:
**

**Question 7:
**Two travelling waves y

_{1}=A sin [k (x – ct)] and y

_{2}= A sin [k (x + ct)] are superimposed on string. The distance between adjacent nodes is

(a) C/π

(b) C/2π

(c) π/2k

(d) π/k

**Question 8:
**A source of sound is moving with constant velocity of 20 ms

^{-1}emitting a note of frequency 1000 Hz. The ratio of frequencies observed by a stationary observer while the source is approaching him and after it

crosses him will be (speed of sound v = 340 ms

^{-1})

(a) 9: 8

(b) 8:9

(c) 1:1

(d) 9:10

**Question 9:
**A table is revolving on its axis at 5 rev/s. A sound source of frequency 1000 Hz is fixed on the table at 70 cm from the axis. The minimum frequency heard by a listener standing at a distance very far from the table will be (speed of sound = 352 ms

^{-1})

(a) 1000 Hz

(b) 1066 Hz

(c) 941 Hz

(d) 352 Hz

**Question 10:
**The wavelength is 120 cm when the source is stationary. If the source is moving with relative velocity of 60 ms

^{-1}towards the observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 ms

^{-1})

(a) 98 cm

(b) 140 cm

(c) 120 cm

(d) 1440 cm

**Question 11:
**An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the -percentage increase in the apparent frequency?

(a) 5%

(b) 20%

(c) zero

(d) 0.5%

**Question 12:
**In the experiment for the determination of the speed of sound in air using the resonance column method, the length of the air column that resonates in the fundamental mode, with a tuning fork is 0.1 m. When this length is changed to 0.35 m, the same tuning fork resonates with the first overtone. Calculate the end correction.

(a) 0.012 m

(b) 0.025 m

(c) 0.05 m

(d) 0.024 m

**Question 13:
**Two bodies M and N of equal masses are suspended from two separate springs of constants k

_{1}and k

_{2}, respectively. If they oscillate with equal maximum velocities, then the amplitudes of M and N are in the ratio of

(a) k

_{1}/k

_{2}

(b) k

_{2}/k

_{1}

(c) √(k

_{1}/k

_{2})

(d) √(k

_{2}/k

_{1})

**Question 14:
**Two simple pendulums of length 0.5 m and 20 m respectively are given small linear displacement in one direction at the same time. They will again be in the phase when the pendulum of shorter length has completed, how many oscillations?

(a) 5

(b) 1

(c) 2

(d) 3

**Question 15:
**A particle is executing SHM with an amplitude of 4 cm. At the mean position the velocity of the particle is 10 cms

^{-1}. The distance of the particle from the mean position when its speed becomes 5 cms

^{-1}is

(a) √3 cm

(b) √5 cm

(c) 2√3 cm

(d) 2√5 cm

**Question 16:
**In a Kundt’s tube experiment, the distance between nodes was 8 cm. If velocity of sound in air is 330 ms

^{-1}and total length of sounding rod is 160 cm, then what is the velocity of sound in rod?

(a) 6800 ms

^{-1}

(b) 7200 ms

^{-1}

(c) 6200 ms

^{-1}

(d) 6600 ms

^{-1}

**Question 17:
**A particle executes SHM between x = -A and x = +A. The time taken for it to go from 0 to A/2 is T

_{1}and to go from A/2 to A is T

_{2}. Then,

(a) T

_{1}<T

_{2}

(b) T

_{1}>T

_{2}

(C) T

_{1}=T

_{2}

(d) T

_{1}= 2T

_{2}

**Question 18:
**A simple pendulum has a time period T

_{1}when on the earth’s surface and T

_{2}when taken to a height R above the earth’s surface, where R is the radius of the earth. The value of T

_{2}/ T

_{1}is

(a) 1

(b) √2

(c) 4

(d) 2

**Question 19:
**The displacement of a particle varies with time according to the relation y = asinωt + bcosωt.

(a) The motion is oscillatory but not SHM

(b) The motion is SHM with amplitude a+b

(c) The motion is SHM with amplitude a

^{2}+ b

^{2}

(d) The motion is SHM with amplitude √(a

^{2}+ b

^{2})

**Question 20:
**The length of a simple pendulum executing SHM is increased by 21%. The percentage increase in the time period of the pendulum of increased length is

(a) 10%.

(b) 11%

(c) 21%

(d) 42%

**Question 21:
**Two tuning forks when sounded together produce 10 beats/s. The first fork has the frequency 5% less than the standard fork and the second has the frequency 8% higher than a standard one. What are the frequencies of the forks?

(a) 73 Hz, 83 Hz

(b) 83 Hz, 93 Hz

(c) 103 Hz, 93 Hz

(d) 113 Hz, 103 Hz

**Question 22:
**A source of sound gives five beats per second, when sounded with another source of frequency 100 s

^{-1}. The second harmonic of the source, together with a source of frequency 205 s

^{-1}gives five beats per second. What is the frequency of the source?

(a) 105 s

^{-1}

(b) 205 s

^{-1}

(c) 95 s

^{-1}

(d) 100 s

^{-1}

**Question 23:
**A column of air at 88° C and a tuning fork produce 6 beats/s when sounded together. When temperature is 16°C the two produce only one beat per second. What is the frequency of tuning fork?

(a) 53.9 Hz

(b) 97.7 Hz

(c) 41.5 Hz

(d) 87.7 Hz

**Question 24:
**A steel wire of length 80 cm and area of cross-section 10

^{-5}m

^{2}is joined with an aluminium wire of length 60 cm and area of cross-section 3×10

^{-5}m

^{2}. The composite string is stretched by a tension 100 N. What is minimum frequency of tuning fork, which can produce standing wave in it with node at the joint? (Given, ρ

_{steel}= 7800 kg m

^{-3}and ρ

_{Al}= 2600 kg m

^{-3})

(a) 87.5 Hz

(b) 97.8 Hz

(c) 67.9 Hz

(d) 89.5 Hz

**Question 25:
**A string of mass 2.5 kg is under a tension of 200 N. The length of the stretched string is 20.0 m. If the transverse jerk is struck at one end of the string, the disturbance will reach the other end in

(a) 1 s

(b) 0.5 s

(c) 2 s

(d) Data insufficient

**Question 26:
**A spring of force constant k is cut into two pieces such that one piece is doubled the length of the other. Then, the longer piece will have a force constant

(a) 2k/3

(b) 3k/2

(c) 3k

(d) 6k

**Question 27:
**The potential energy of a simple harmonic oscillator whan the particle is half way to its end point is

(a) E/8

(b) E/4

(C) E/2

(d) 2E/3

**Question 28:
**An elastic ball is dropped from a height h on an elastic floor. It collides against the floor elastically and rebounds to the same height. What is the nature of its motion and time period of return to the starting point?

(a) SHM, √(8h/g )

(b) Oscillatory,√(8h/g )

(c) SHM, 2√(h/g)

(d) Oscillatory, 2√(h/g)

**Question 29:
**In a transverse progressive wave of amplitude A, the maximum particle velocity is four times the wave velocity. Then, the wavelength of the wave is

(a) πA/2

(b) πA/4

(c) πA

(d) 2πA

**Question 30:
**When a mass m is connected individually to two springs S

_{1}and S

_{2}, the oscillation frequencies are ν

_{1}and ν

_{2}. If the same mass is attached to the two springs as shown in figure the oscillation frequency would be

**Question 31:
**The equation of a simple harmonic is given by y = 3sin π/2(50t-x),

where, x and y are in metres and t is in seconds. The ratio of maximum particle velocity to the wave velocity is

(a) 2π

(b) 3π/2

(c) 3π

(d) 2π/3

**Question 32:
**A solid cylinder of mass 3 kg is rolling on a horizontal surface with velocity 4ms

^{-1}. It collides with a horizontal spring of force constant 200 Nm

^{-1}. The maxirinum compression produced in the spring will be

(a) 0.5 m

(b) 0.6 m

(c) 0.7 m

(d) 0.2 m

**Question 33:
**The amplitude of a particle executing SHM is 4 cm. As the mean position, the speed of the particle is 16 cm/s. The distance of the particle from the mean position at which the speed of the particle becomes 8 √3 cm/s will be

(a) 2√3 cm

(b) √3 cm

(c) 1 cm

(d) 2 cm

**Question 34:
**A simple harmonic oscillator consists of a particle of mass m and an ideal spring with spring constant k. The particle oscillates with a time period 7. The spring is cut into two equal parts. If one part oscillates with the same particle, the time period will be

(a) 2T

(b) √2T

(c) T/√2

(d) T/2

**Question 35:
**A train moving at a speed of 220 ms

^{-1}towards a stationary object, emits a sound of frequency 1000 Hz. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is 330 ms

^{-1})

(a) 3500 Hz

(b) 4000 Hz

(c) 5000 Hz

(d) 3000 Hz

**Question 36:
**When a certain volume of water is subjected to increase of 100 kPa pressure, the volume of water decreases by 0.005%. The speed of sound in water must be

(a) 140 m/s

(b) 300 m/s

(c) 1400 m/s

(d) 5000 m/s

**Question 37:
**

**Question 38:
**The frequency of the first overtone of a closed pipe of length l

_{1}, is equal to that of the first overtone of an open pipe of length l

_{2}. The ratio of their lengths (l

_{1}: l

_{2}) is

(a) 2 : 3

(b) 4 : 5

(c) 3 : 5

(d) 3 : 4

**Question 39:
**A particle is executing SHM. Then, the graph of velocity as a function of displacement is a/an

(a) straight line

(b) circle

(c) ellipse

(d) hyperbola

**Question 40:
**A long spring, when stretched by a distance x, has potential energy U. On increasing the stretching to nx, the potential energy of the spring will be

(a) U/n

(b) nU

(c) n

^{2}U

(d) U/n

^{2}

**Question 41:
**If the maximum velocity and acceleration of a particle executing SHM are equal in magnitude the time period will be

(a) 1.57 s

(b) 3.14 s

(c) 6.28 s

(d) 12.56 s

**Question 42:
**Two pendulums have time period T and 5T/4. They starts SHM at the same time from the mean position. What will be the phase difference between them after the bigger pendulum completed one oscillation?

(a) 45°

(b) 90°

(c) 60°

(d) 30°

**Question 43:
**A sound has an intensity of 2×10

^{-8}W/m

^{2}. Its intensity level in decibel is (log

_{10}2 = 0.3)

(a) 23

(b) 3

(c) 43

(d) 4.3

**Question 44:
**Two waves having the intensities in the atio of 9:1 produce interference. The ratio of maximum to minimum intensity is equal to

(a) 10: 8

(b) 9 : 1

(c) 4 : 1

(d) 2 : 1

**Question 45:
**Which of the following is different from others?

(a) Wavelength

(b) Velocity

(c) Frequency

(d) Amplitude

**Direction (Q. Nos. 46-50):** In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as

(a) If both Assertion and Reason are true and Reason is the correct explanation of assertion ,

(b) If both Assertion and Reason are true but the Reason is not the correct explanation of Assertion

(c) If Assertion is true but Reason is false

(d) If both Assertion and Reason are false

**Question 46:
Assertion (A): **Simple Harmonic Motion (SHM) is not a uniform motion.

**It is the projection of uniform circular motion.**

Reason (R):

Reason (R):

**Question 47:
Assertion (A): **A hole were drilled through the centre of earth and a ball is dropped into the hole at one end, it will not get out of other end of the hole.

**It will come out of the other end normally.**

Reason (R):

Reason (R):

**Question 48:
Assertion (A): **A tuning fork is in resonance with a closed pipe. But the same tuning fork cannot be in resonance with an open pipe of the same length.

**The same tuning fork will not be in resonance with open pipe of same length due to end correction of pipe.**

Reason (R):

Reason (R):

**Question 49:
Assertion (A): **In everyday life, the Doppler’s effect is observed readily for sound waves than light waves.

**Velocity of light is greater than the sound.**

Reason (R):

Reason (R):

**Question 50:
Assertion (A): **Velocity of particles while crossing mean position (in stationary waves) varies from maximum at anti-nodes to zero at nodes.

**Amplitude of vibration at anti-nodes is maximum and at nodes, the amplitude is zero and all particles between two successive nodes cross the mean position together.**

Reason (R):

Reason (R):

### Answers:

### Hints And Solutions: