Question

15. A boy throws a ball upwards from the ground, it reaches
back to him after 4 s. (a) With what velocity was it
thrown? (b) What was the maximum height reached?
Take g = 10 m s-2.​

Answer 1

Answer:

80m

Explanation:

have to find the initial velocity

v=0

g= -10m/s2

t=4s

(a) v=u+at

   0=u+ (-10) x 4

   0=u-40

   u=40m/s2

(b) 2as=v2-u2

    2 x (-10) x s = 0sq. - 40sq.

   -20s=-1600

     s=-1600/-20= 80m

if the total height is asked after the ball comes down, 80+80=160m

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