A body of mass 500kg is thrown vertically upwards wiyh an initial speed of 200m/s. On the return journey its speed at the starting point will be? the options are A) 2000m/s B) 200m/s C) 980m/s D) 1000m/s

Asked by yasho1710 | 4th Sep, 2010, 08:36: AM

Expert Answer:

the body's motion can be divided in two parts:
1. going up
2. returning back, down
Motion 1. Initial velocity , u = 200 m/s
              Final velocity, v = 0 m/s (Velocity when it reaches the highest point is zero)
              Acceleration, a = -10 m/s2     (since moving against gravity)
              Using v2 = u2 + 2as,
              Distance traveled in upward direction, s = 2000m
Motion 2. The body will trace back the 2000m to reach back to the starting point.
              Therefore, s = 2000m
                             u = 0 m/s (velocity at highest point)
                             a = +10 m/s2 (moving along gravity)
               Using v2 = u2 + 2as
                        v2  =  0 + (2x10x2000)
                        v  = 200 m/s.

Answered by  | 4th Sep, 2010, 11:55: PM

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