363464
A person jumps from the \({5^{\text {th }}}\) storey of a building with load on his head. The weight experienced by him before reaching the earth will be
1 zero
2 \(g\,kg\,wt\)
3 \(m(g + a)\)
4 \(mg\)
Explanation:
The free body diagram of the person of mass \({m}\) in air is shown below Here, \({N=}\) Normal force by the weight on the man \({m g=}\) weight of man \({a=}\) acceleration of man Balancing forces we get, \({N+m g=m a}\) \(=N+m g=m g \Rightarrow N=0 \quad[\because a=g]\). So correct option is (1)
PHXI05:LAWS OF MOTION
363465
A metre scale is moving with uniform velocity. This implies
1 The force acting on the scale is zero, but a torque about the centre of mass can act on the scale
2 The force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero
3 The total force acting on it need not be zero but the torque on it is zero
4 Neither the force nor the torque need to be zero
Explanation:
When a metre scale is moving with uniform velocity, the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero.
NCERT Exemplar
PHXI05:LAWS OF MOTION
363466
If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will
1 Go on increasing
2 Go on decreasing
3 First increase and then decrese
4 Remain the same
Explanation:
Initially due to upward acceleration apparent weight of the body increases but then it decreases due to decrease in gravity.
363464
A person jumps from the \({5^{\text {th }}}\) storey of a building with load on his head. The weight experienced by him before reaching the earth will be
1 zero
2 \(g\,kg\,wt\)
3 \(m(g + a)\)
4 \(mg\)
Explanation:
The free body diagram of the person of mass \({m}\) in air is shown below Here, \({N=}\) Normal force by the weight on the man \({m g=}\) weight of man \({a=}\) acceleration of man Balancing forces we get, \({N+m g=m a}\) \(=N+m g=m g \Rightarrow N=0 \quad[\because a=g]\). So correct option is (1)
PHXI05:LAWS OF MOTION
363465
A metre scale is moving with uniform velocity. This implies
1 The force acting on the scale is zero, but a torque about the centre of mass can act on the scale
2 The force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero
3 The total force acting on it need not be zero but the torque on it is zero
4 Neither the force nor the torque need to be zero
Explanation:
When a metre scale is moving with uniform velocity, the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero.
NCERT Exemplar
PHXI05:LAWS OF MOTION
363466
If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will
1 Go on increasing
2 Go on decreasing
3 First increase and then decrese
4 Remain the same
Explanation:
Initially due to upward acceleration apparent weight of the body increases but then it decreases due to decrease in gravity.
363464
A person jumps from the \({5^{\text {th }}}\) storey of a building with load on his head. The weight experienced by him before reaching the earth will be
1 zero
2 \(g\,kg\,wt\)
3 \(m(g + a)\)
4 \(mg\)
Explanation:
The free body diagram of the person of mass \({m}\) in air is shown below Here, \({N=}\) Normal force by the weight on the man \({m g=}\) weight of man \({a=}\) acceleration of man Balancing forces we get, \({N+m g=m a}\) \(=N+m g=m g \Rightarrow N=0 \quad[\because a=g]\). So correct option is (1)
PHXI05:LAWS OF MOTION
363465
A metre scale is moving with uniform velocity. This implies
1 The force acting on the scale is zero, but a torque about the centre of mass can act on the scale
2 The force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero
3 The total force acting on it need not be zero but the torque on it is zero
4 Neither the force nor the torque need to be zero
Explanation:
When a metre scale is moving with uniform velocity, the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero.
NCERT Exemplar
PHXI05:LAWS OF MOTION
363466
If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will
1 Go on increasing
2 Go on decreasing
3 First increase and then decrese
4 Remain the same
Explanation:
Initially due to upward acceleration apparent weight of the body increases but then it decreases due to decrease in gravity.
