# Physics MCQs Part 13

**121. An explosion blows a rocket into three parts. Two piece go off at right angles to each other, a 100 kg piece at 12 m/s and 200 kg piece at 8 m/s. Then mass of third piece which flies off at an angle of 53° is**

A. 10 kg

B. 20 kg

**C. 30 kg**

D. 40 kg

**122. A tuning fork of frequency 512 produces 6 beats in 1 second, when vibrating along**

**with**

**a vibrating segment of a monometer wire. The frequency of the vibration of sonometer**

**wire is**

A. 512

B. 506

C. 518

**D. 506 and 518**

**123. A tuning fork of frequency 645 Hz, gives resonance for 0.5 m column of hydrogen gas enclosed in a pipe closed at one end. The speed of sound in hydrogen will be equal to**

**A. 2580 m/s**

B. 322.5 m/s

C. 645 m/s

D. 1290 m/s

**124. The pitch of a sound is determined by**

**A. Frequency**

B. Speed

C. Direction

D. Number of beats

**125. At the mean position of vibration, the velocity of the vibrating particle is**

A. Zero

B. Infinity

**C. Maximum**

D. None of the above

**126. A particle moving with S.H.M passes through two points A and B, with the same**

**velocity, having occupied 2 seconds in passing from A to B; after another 2 seconds it returns to B. The period is**

A. 2 seconds

B. 4 seconds

C. 5 seconds

**D. 8 seconds**

**127. Energy is not transferred in a standing wave**

A. False

B. Uncertain

**C. True**

D. None of these

**128. Two similar open organ pipes when sounded together produce 7 beats/sec. If their**

**lengths are in the ration of 50: 51, then the ration of their frequencies will be**

A. 357:350

B. 50:51

**C. 51:50**

D. 1:7

**129. The Laplaces's correction in the expression for the velocity of sound given by Newton is**

**needed because sound waves**

A. Are longitudinal

B. Propagate isothermally

**C. Propagate adiabatically**

D. Are of long wavelengths

**130. What is the shape of the liquid meniscus in a capillary tube placed in a liquid that wets**

**the surface of the tube?**

**A. Flat**

B. Concave downwards

C. Convex up

D. None of the above is correct