A ball is thrown directly upwards with a velocity of +20m/s. At the end of 4s, it's velocity will be closest ?

Question

to..

a) -50m/s

b)-30m/s

c) -20m/s

Answer 1

v = u + at

u = +20m/s

a = -g = -9.8 m/s^2 (negative because ball is thrown upward and gravity is downward)

t = 4s

v = 20 - 9.8 * 4 = 20 - 39.2 = -19.2 m/s

Out of given options, it is closest to (c)

Answer 2

Final velocity =

20+(-9.8*4) = -19.2 m/s

c)

Answer 3

v = -gt + v0 = -9.8*4 + 20 = 59.2 m/s

Answer 4

vf = v0 + at

vf = 20 -9.81*4

vf = -19.4 m/s

vf = -20 m/s .... C