A bullet emerge from a barrel of length 1.2 m with a speed of 640 ms-1 . Assuming constant acceleration, the approximate time that it spends in the barrel after the gun is fired is
4 ms
40 ms
400 μs
1 s
A body of mass 3 kg acted upon by a constant force is displaced by S' metre, given by relation , where t is in second. Work done by the force in 2 is
A beaker of radius 15 cm is filled with a liquid of surface tension 0.75 N/m. Force across an imaginary diameter on the surface of the liquid is
0.075 N
1.5 × 10-2 N
0.225 N
2.25 × 10-2 N
Two springs are joined and attached to a mass of 16 kg. The system is then suspended vertically from a rigid support. The spring constant of the two springs are k1 and k2 respectively. The period of vertical oscillations of the system will be
B.
The two springs are in series. Therefore, the time period is
The equation of a progressive wave can be given by y = 15 sin (660 − 0.02 x) cm. The frequency of the wave is
330 Hz
342 Hz
365 Hz
660 Hz
A hollow cylinder with both sides open generates a frequency f in air. When the cylinder vertically immersed into water by half its length the frequency will be
f
2f
f/2
f/4
Two stretched strings have lengths land 2l while tension are T and 4 T respectively. If they are made of same material the ratio of their frequency is
2 : 1
1 : 2
1 : 1
1 : 4
When sound is produced in an aeroplane moving with a velocity of 200 m/s horizontal its echo is heard after 10 s. If velocity of sound in air is 300 ms-1 the elevation of aircraft is
250 m
1250 m
2500 m
Two tuning forks of frequency n1 and n2 produces n beats per second. If n1 and n2 are known, n1 may be given by
n2n
n2 ± n
A car moving with a velocity of 36 km/h crosses a siren of frequency 500 Hz. The apparent frequency of siren after passing it will be
520 Hz
485 Hz
540 Hz
460 Hz