An express train is moving with a velocity `v_1`. Its driver finds another train is movig on the same track in the same direction with velocity `v_2`. To escape collision, driver applies a retardation a on the train. The minimum time of escaping collision be

A train 100 m long is moving with a velocity of 60 kmh^-1 . Find the time it takes to cross the bridge 1 km long.

Escape velocity on a planet is v_e , if the radius of the planet remains same and mass becomes four times, the escape velocity becomes

A 130 m long train is moving in a direction with speed 20 ms^-1 . Another train moving with 30ms^-1 and 120 m long crosses the first train in a time

A car travelling on a straight track moves with unifrom velocity of v_1 for some time and uniform velocity V_2 for the next equal time.The average velocity v is given by

Two objects, each of mass 1.5 kg, are moving in the same straight line but in the opposite directions. The velocity of each object is 2.5 ms^(-1) before the collision during which they stick together. What will be the velocity of combined object after collision ?