A uniform pole PQ, 30 m long and of mass
4 kg is carried by a boy at P and a man
8 m away from Q. Find the distance from
P where a mass of 20 kg should be attached
so that the man′s support is twice that
of the boy, if the system is in equilibrium
[Take g=10ms^(−2) ]
Two passenger trains, A and B, 450km apart,
start to move towards each other at the
same time and meet after 2 hours. If train B,
travels (8/7) as fast as train A, find the speed
of each train.
An earth-based observer sees rocket A
moving at 0.70c directly towards rocket
B,which is moving towards A at 0.80c.
How fast does rocket A sees rocket B
approaching?