A man weighing 70 kg is coming down in lift. If the cable of the lift brakes sudden, the weight of the man would become

A given conductor carrying a current of 1 ampere. It produces an amount of heat equal to 2000 J. If the current through the conductor is doubled, then the amount of heat produced will be

A lady is standing in front of a plane mirror at a distance of 1 m from it. She walks 60 cm towards the mirror. The distance of her image now from herself (ignoring the thickness of the mirror) is

The brightness of a star depends on its