Question

A ball is thrown vertically upwards. It goes to a
height 20 m and then returns to the ground. Taking
acceleration due to gravity g to be 10 m s-2, find :
(a) the inital velocity of the ball
(b) the final velocity of the ball on reaching the
ground and
(c) the total time of journey of the ball.​

Answer 1

Answer:

Answer:

a) initial velocity = u = 20 m/s

c)  t = 4 s

b) final velocity = 0 m.s

Explanation:

(a)

h = 20 m

final velocity = v = 0 m/s

initial velocity = u = ?

2 (- g) h = v² - u²        g is -ve because body is moving against gravity

-(2x10x20)  = 0 - u²

u = 20 m/s

(b)

v = u - gt

0 = 20 - 10 t

t = 2 s

total time is 4 s