CBSE
Multiple Choice Questionsn balls each of mass m and velocity v collide with a wall, assume that the collisions are perfectly elastic. The pressure exerted per second on the wall is
3 mnv
mnv
2mnv
none
A smooth sphere of mass m moving with velocity u directly collides elastically with another sphere of mass M at rest. After collision their final velocities are V and v respectively. The value of v is
A water film is made between two 10 cm long straight wires and at a distance of 0.5 cm. If distance between the wires is increased by 1 mm, then work done will be (T = 7.2 x 10-2N/m)
7.22 × 10-6 J
1.44 × 10-5 J
2.88 × 10-5 J
5.76 × 10-5 J
A particle performing uniform circular motion has angular momentum L. If its angular frequency is doubled and its kinetic energy halved, then the new angular momentum is
2L
4L
A spring scale is adjusted to read zero. Particles of mass 1 g fall on the pan of the scale and collide elastically and they rebound upward with the same speed. If the height of fall of particles is 2 m and their rate of collision is 100 particles per second, then the scale reading in grams will be (g =9.8 m/s)?
1000 g
1100 g
1200 g
1252 g
A cone filled with water is revolved in a vertical circle of radius 4 m and the water does not fall down. What must be the maximum period of revolution?
2 sec
4 sec
1 sec
6 sec
A massless spring of natural length of 0.5 m and spring constant 50 N/m has one end fixed and the other end attached to mass of 250 g. The spring mass system is on a smooth floor. The mass is pulled until the length of the spring is 0.6 and then released from rest. The kinetic energy of the mass when the length of the spring is 0.5 m is
0.0176 J
2.25 J
6.25 J
9 J
A car and a container, moving with equal kinetic energies are stopped by applying a negative acceleration. Then
container will move less distance before being stopped
both will become stationary after moving some distance
car will move less distance before being stopped
none of the above
The ground state energy of hydrogen atom is -13.6 eV. The kinetic energy of the electron
in this state is
27.2 eV
13.6 eV
6.8 eV
3.4 eV
The momentum of two masses m1 and m2 are same. The ratio of their kinetic energies E1 and E2 is
m1 : m2
m2 : m1
m12 : m22
