A body of mass $32 \,kg$ is suspended by a spring balance from the roof of a vertically operating lift and going downward from rest. At the instants the lift has covered $20 \,m$ and $50 \,m$, the spring balance showed $30 \,kg$ and $36 \,kg$ respectively. Then the velocity of the lift is:
The two arms of a balance are of unequal length. An object when placed in the left pan of the balance weighs 4kg. The same object when placed in the right pan of the balance weighs 9 kg. The actual (or) true mass of the object is
A $20 N$ metal block is suspended by a spring balance. A beaker containing some water is placed on a weighing machine which reads $40 N$. The spring balance is now lowered so that the block gets immersed in the water. The spring balance now reads $16 N$4. The reading of the weighing machine will be -
Two equal masses m and m are hung from a spring balance whose scale pans differ in vertical height by h. If $\rho$ is the mean density of earth ,then what is the error in weighing?
A boy whose mass is $50$ kg stands on spring balance inside a lift. The lift starts to ascend with an acceleration of $2{ m/s }^{ -2 }$. The reading of the machine or balance (g = 10${ m/s }^{ -2 }$) is
A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity g the reading of the spring balance will be
A bird is sitting in a wire cage hanging form the spring balance. Let the reading of the spring balance be $W _1$. If the bird flies about inside the cage, the reading of the spring balance is $W _2$. Which of the following is true :-
A false balance is such that the beam remains horizontal when the pans are empty. An object weighs ${ w } _{ 1 }$ when placed in one pan and ${ w } _{ 2 }$ when placed in the other pan. Then the weight W of the object is
An object hangs from a spring balance. The balance indicates $30 { N }$ in air and $20 { N }$ when the object is submerged-in.water. What does the balance indicate when the object is submerged in a liquid. with a density that is half that of water ?
A man is standing on a weighting machine with a block in his hand. The machine records $W$. When he takes the block upwards with some acceleration the machine records $W _1$. When he takes the block down with some acceleration, the machine records $W _2$. Then choose correct option