How much work must the man do, to accelerate the crate to speed 1m/s?
2007-10-04 04:11:22 · 2 answers · asked by Alexander 6 in Science & Mathematics ➔ Physics
When the man pushes the crate,the crate exerts equal and opposite force on the man.
As external force is absent, momentum is conserved.
Momentum imparted to the crate=mass'm' x velocity 'u' =200x1=200 Ns
Momentum imparted to the man = 200 Ns
speed of man=momentum / mass =200 /100 = 2 m/s
Kinetic energy gained by crate ' E1' = (1/2)mu^2=(1/2)200x1=100J
Kinetic energy gained by man 'E2' = (1/2)100x2^2=200J
The increase in kinetic energies of crate and man is due to work done by the man
Work 'W' done by man = E1+E2=100+200=300 J
Man does 300 J of work to accelerate the crate to a speed of 1 m/s
2007-10-04 05:19:03 · answer #1 · answered by ukmudgal 6 · 4⤊ 0⤋
Poor man
2007-10-04 04:17:00 · answer #2 · answered by Edward 7 · 1⤊ 1⤋