A body of mass m = 10–2 kg is moving in a medium and experiences a frictional force F = –kv2. Its initial speed is v0 = 10 ms–1. If, after 10 s, its energy is 1/8 mv02,the value of k will be
10-4 kg m-1
10–1 kg m–1 s–1
10-3 kg m-1
10-3 kg m-1
The variation of acceleration due to gravity g with distance d from centre of the earth is best represented by (R = Earth's radius)
A particle A of mass m and initial velocity v collides with a particle B of mass m/2 which is at rest. The collision is head on, and elastic. The ratio of the de-Broglie wavelengths λA to λB after the collision is
A time-dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 sec. will be
9J
18 J
4.5 J
4.5 J
A body is thrown vertically upwards. Which one of the following graphs correctly represent the velocity vs time?
A particle is executing simple harmonic motion with a time period T. AT time t = 0, it is at its position of equilibrium. The kinetic energy-time graph of the particle will look like
The temperature of an open room of volume 30 m3 increases from 17°C to 27°C due to sunshine. The atmospheric pressure in the room remains 1 × 105 Pa. If ni and nf are the numbers of molecules in the room before and after heating, then nf – ni will be
2.5 x 1025
-2.5 x 1025
-1.61 x 1023
-1.61 x 1023
The following observations were taken for determining surface tension T of water by the capillary method :
Diameter of capillary, D = 1.25 × 10–2 m rise of water, h = 1.45 × 10–2 m
Using g = 9.80 m/s2 and the simplified relation T = (rhg/2) x103 n/m, the possible error in surface tension is closest to:
2.4%
10%
0.15%
0.15%
D.
0.15%