A boat at anchor is rocked by waves whose troughs are 150 m apart and whose velocity is 30 m/s.How often do the crests reach the boat ?
0.2 s
10 s
0.5 s
5 s
The speed of the bob of an oscillating pendulum is zero
at the mean position
at an extreme position
between the mean position and the left extreme
between the mean position and the right extreme
In SONAR we use
ultrasonic waves
infrasonic waves
radio waves
audible sound waves
An object moving at a speed greater than that of sound is said to be moving at:
ultrasonic speed
sonic speed
infrasonic speed
supersonic speed
A bat can hear sound at frequencies upto 120 kHz.Determine the wavelength of sound in air at this frequency.Take the speed of sound in air as 344 m/s
2.9 x 10-3 m
4.5 x 10-3 m
2.5 x 10-3 m
1.8 x 10-3 m
Longitudinal waves cannot travel through
vacuum
solids
liquids
gases
S.I unit of wave length (λ) is
centimetre
millimetre
killometre
metre
A stone is dropped into a well,44.1 metres deep.The sound of the splash is heard 3.13 seconds after the stone is dropped.Find the velocity of sound in air.
339.2 m/s
350 m/s
258.3 m/s
450 m/s
A simple pendulum has a metal bob which is negatively charged.If it is allowed to oscillate above a positively charged metallic plate then its time period will
increase
decrease
remain the same
become zero
The bob of a pendulum moves from the mean position to an extreme position in 0.28 seconds.Then the time period of the pendulum is
2.24 seconds
1.12 seconds
0.84 seconds
3.84 seconds
