Velocity-time graph for a body of mass 10 kg is shown in figure. Work-done on the body in first two seconds of the motion is :
12000 J
−12000 J
−45000 J
−9300 J
As we discussed in
Net work done by all the forces give the change in kinetic energy -
- wherein
Initial velocity = 50 m/s
Final velocity = 0
Therefore
Therefore at any time t, velocity is
v = 50 - 5 t
at t = 0, v = 50 m/s
at t = 2s, v = 40 m/s
Therefore done in first 2 second will be change in kinetic energy
Therefore
W = - 4500 J
Option 1)
12000 J
This is an incorrect option.
Option 2)
−12000 J
This is an incorrect option.
Option 3)
−45000 J
This is the correct option.
Option 4)
−9300 J
This is an incorrect option.
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