Physics Test - ...

A stationary bomb of mass 17 kg explodes into three pieces of masses 4 kg, 5 kg and 8 kg. Of these 4 kg and 5 kg masses are ejected with speeds of 15 ms⁻¹ and 16 ms⁻¹ respectively in mutually perpendicular directions. The speed with which the piece of mass 8 kg ejected is

A mass is attached to one end of a spring of spring constant k. The spring is stretched and then released such that its amplitude of oscillation is A. For a displacement y from the mean position, if the kinetic energy is 44% of its potential energy, then y in terms of A is

A man pulls a loaded sledge of mass 60 kg along a horizontal surface at constant velocity as shown in figure. The coefficient of kinetic friction between the sledge and the surface is 0.15. The tension in the rope during pulling when it makes an angle of φ = 40 ° with the horizontal is (cos 40 ° = 0.766, sin 40 ° = 0.643 and g = 10 ms^-2)

Two identical parallel plate capacitors are connected to a battery with the switch S closed. After some time S is opened and the free space between the plates of the capacitors is filled with a material of dielectric constant K. The ratio of the total electrostatic energies stored after the introduction of the dielectric to the energy stored before introduction of dielectric is-

A beam of light traveling in water strikes a glass plate which is also immersed in water. When the angle of incidence is 50 °, the reflected beam is found to be plane polarised. The refractive index of water is 4/3. The refractive index of the glass plate is (Given tan 50 ° = 1.198)

At a given instant there are 25% of undecayed radioactive nuclei in a sample. After 20s, the number of undecayed nuclei reduces to 12.5%. The extra time required in which the number of undecayed nuclei will further reduce to 3.125% of the sample is-

Capacitors C₁ = 1 μF and C₂ = 2 μF are separately charged from the same battery. They are allowed to discharge separately through equal resistors at t = 0. Then

Force applied by water stream depends on density of water (ρ) velocity of the stream (v) and cross sectional area of the stream (A). The expression of the force should be :

The SI unit of mobility of charges (μ) is :