A rigid container with thermally insulated walls contains a coil of resistance 100 Ω, carrying current 1 A. Change in internal energy after 5 min will be
Two spherical bodies of mass M and 5M and radii R and 2R respectively are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then distance covered by the smaller body just before collision is
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Two particles of mass m each are tied at the ends of a light string of length 2a. The whole system is kept on a frictionless horizontal surface with the string held tight so that each mass is at a distance a from the centre P (as shown in the figure). Now, the mid-point of the string is pulled vertically upwards with a small but constant force F. As a result, the particles move towards each other on the surface. The magnitude of acceleration, when the separation between them becomes 2x, is
Statement I : The formula connecting u, υ and f for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.
Statement II : Laws of reflections are strictly valid for plane surfaces, but not for large spherical surfaces.
A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The current I, in the circuit will be
The pressure of a medium is changed from 1.01 × 105 Pa to 1.165 × 105 Pa and change in volume is 10% keeping temperature constant. The bulk modulus of the medium is
An inductor of inductance 2.0 mH is connected across a charged capacitor of capacitance 5.0 μF and the resulting L-C circuit is set oscillating at its natural frequency. Let Q denote the instantaneous charge on the capacitor and I the current in the circuit. It is found that the maximum value of Q is 200 μC. When Q = 100 μC, what is the value of
A simple pendulum is oscillating without damping. When the displacement of the bob is less than maximum, its acceleration vector is correctly shown in
A charge +q is fixed at each of the points x = x0, x = 3x0, x = 5x0 ........∞ on the x−axis and a charge −q is fixed at each of the points x = 2x0, x = 4x0, x = 6x0 .........,∞. Here, x0 is a positive constant. Take the electric potential at a point due to a charge Q at a distance r from it to be Then the potential at the origin due to the above system of charges is
The earth radiates in the infra-red region of the spectrum. The wavelength of the maximum intensity of the spectrum is correctly given by
The half-life of 131I is 8 days Given a sample of 131I at time t = 0, we can assert that
Two particles A and B of masses mA and mB respectively and having the same charge are moving in a plane. A uniform magnetic field exists perpendicular to this plane. The speeds of the particles are vA and vB respectively and the trajectories are as shown in the figure. Then
In common base mode of a transistor, the collector current is 5.488 mA for an emitter current of 5.60 mA. The value of the base current amplification factor, β will be
Two particles A and B initially at rest, move towards each other, under the mutual force of attraction. At an instance when the speed of A is v and the speed of B is 2v, the speed of the centre of mass(CM) is
A block of mass 5 kg is moving in x-direction with a constant speed 20 m/s. Now it is subjected to a retarding force Fr = – 0.2 x J/m during its travel from x = 10 m to x = 20 m. Its final velocity will be nearly
When two spheres of equal masses undergo oblique elastic collision with one of them at rest initially, after collision they will move
Two springs of spring constants 500 N m–1 and 500 N m–1 are stretched with force 100 N and 200 N respectively. They have potential energy in the ratio of
Which of the diagram shown in figure represents the variation of total mechanical energy of pendulum oscillating in air as a function of time?
An object has displacement from position vector
under the effect of a force The work done by this force will be
A bus of mass 5 metric tonne is pulled at a speed of 18 km/h on a smooth inclination 1 in 10. Power of the engine is
A ball A moving with certain velocity collides head on with another body B of the same mass at rest. If the coefficient of restitution is 3/4. The ratio of velocity A and B after collision is
A force of 1 N acts on a 1 kg mass for 1 second which is initially at rest. In another case 1 N force acts on 1 kg mass which is initially at rest and moves it through 1 m. The ratio of kinetic energy in the two cases is
A body is being raised to a height h from the surface of earth. What is the sign of work done by applied force and gravitational force respectively?
A force acting on a body maintains its velocity If rate of change of kinetic energy of the body is zero, then the value of α will be
A body is initially at rest. It undergoes one dimensional motion with constant acceleration. The power delivered to it at time t is proportional to
A ball of mass m collides with a wall with speed v and rebounds on the same line with the same speed. If mass of the wall is taken infinite at rest, then work done by the ball on the wall is
Statement-A: Work done by frictional force is always negative.
Statement-B: A body at rest can have mechanical energy.
1 videos|26 docs|121 tests
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1 videos|26 docs|121 tests
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