Physics, asked by rohirestle, 1 year ago

I have 2 controversy question
1. A girl standing on a stationary lift throws a ball upwards with initial speed 50 m/s the time taken by the ball to return to her hands is?
2 .a player throws a ball upwards with an initial speed 30m/s how long does the ball take to return to the players hand?
Why can't we I use 1st law of motion for the first case(v=u+at)


rohirestle: Pls guys give me a related one

Answers

Answered by Jindalnayan
1
1. Simply apply 2nd equation as,
Displacement = 0
Initial velocity (u) = 50 m/s
a = - g = - 10 m/s^2
s = ut + 1/2 at^2
0 = 50(t) + 1/2 (-10) t^2
0 = 5t (10 - t)
Total time taken by ball to return to her hands = 10 sec


U can also apply 1 equation but when u apply 1 equation the time u will get will be the time taken by ball to reach maximum height.... So in order to calculate total time... U have to multiply calculated time by 2...

Similarly u can solve 2 question

Hope it helps... ☺

Jindalnayan: i think answer of 2 question should be 6 sec
rohirestle: HEY BRILLIANT
Jindalnayan: Thnx
rohirestle: i too got but i couldnt understant that
Jindalnayan: what problem r u facing with??
rohirestle: the thing i use 1st equation i get only the time to reach maximum i need clarity yar pls
Jindalnayan: when body is moving upward then v = 0 so when u put this value in 1 equation u will get the time taken by ball upto the point when its velocity will be 0
rohirestle: oh my goodness i got it
Jindalnayan: but when body is moving downward it has some final velocity so that's why 2 equation is more appropriate
rohirestle: OKAYYY
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