Physics Test - ...

Two identical cars having like charges and placed at a distance R apart repel each other with a certain force. They are brought in contact and then moved apart to a distance equal to 1/4^th their initial separation. The force of repulsion between them increases 20 times in comparison with the initial value. The ratio of their initial charges (Given Q₁>Q₂)

A wall made up of two layer X and Y. The thickness of the two layers is the same, but materials are different. The thermal conductivity of X is thrice than that of Y. In thermal equilibrium, the temperature difference between the two ends is 56^oC. Then the difference of temperature across wall X is

A box is floating in the river of speed 5m/s. The position of the block is shown in the figure at t=0. A stone is thrown from point O at time t = 0 with a velocity$v=(v_1\hat{ı}+v_2\hat{ȷ}+40\hat{k})m/s.$Find the value of$v_1,v_2$such that the stone hits the box.

A concave mirror of radius of curvature h is placed at the bottom of a tank containing a liquid of refractive index µ up to a depth d. An object O is placed at height h above the bottom of the mirror. Outside the liquid, an observer M views the object and its image in the mirror. The apparent distance between these two will be

A pendulum bob of mass M = 80 gm connected to the end of a string of length L = 5 m is released from rest from horizontal position as shown in the figure. At the lowest point, the bob makes an elastic collision with a stationary box of mass 8M, which is kept on a friction less surface. Then the tension in the string just after the impact is

A stationary bomb explodes into two parts of masses 3 kg3 kg and 1 kg1 kg. The total KE of the two parts after explosion is 2400 J2400 J. The KE of the smaller parts is :

Three identical cars A,B and C are moving at the same speed on three bridges. The car A goes on a plane bridge, B on a bridge convex upward and C goes on a bridge concave upward. Let FA, FB and FC be the normal force exerted by the cars on the bridges when they are at the middle of bridges.

The charged particle 5×1020 will flow per sec through a heater. What is the current passed through it ?

A wheel having a diameter of 3 m starts from rest and accelerates uniformly to an angular velocity of 210 r.p.m. in 5 seconds. Angular acceleration of the wheel is.