A weight is suspended from the ceiling of a lift by a spring balance. When the lift is stationary the spring balance reads $W$. If the lift suddenly falls freely under gravity, the reading on the spring balance will be

The acceleration due to gravity on the surface of earth is $g$. If the diameter of earth reduces to half of its original value and mass remains constant, then acceleration due to gravity on the surface of earth would be :

A mass falls from a helght $h$ and its time of fall $t$ is recorded in terms of time period $T$ of a simple pendulum. On the surface of earth it is found that $t =2 T$. The entre setup is taken on the surface of another planet whose mass is half of that of earth and radius the same. Same experiment is repeated and corresponding times noted as $t'$ and $T'$.

If the mass of the Sun were ten times smaller  and the universal gravitational constant were ten times larger in magnitude, which of the following is not correct? 

During motion of a man from equator to pole of earth, its weight will ....... $\%$ (neglect the effect of change in the radius of earth)

The height ${ }^{\prime} h ^{\prime}$ at which the weight of a body will be the same as that at the same depth $'h'$ from the surface of the earth is (Radius of the earth is $R$ and effect of the rotation of the earth is neglected):