Question

An athlete jumps vertically and attains a height of 1.29m what is his initial velocity? And how much time does he take to reach this height and then return to the ground?

Answer 1

Answer:

initial velocity = 5.02 m/s ; time taken to reach height = 0.51 second

time taken to reach ground = 1.02 second

Explanation:

vertically maximum height attain by athletic , h = 1.29 m

acceleration due to gravity , g = -9.8 m / s^2  [motion in opposite direction ]

initial velocity , u = ?

final velocity , v = 0    

time taken , t = ?

v^2 -u^2 = 2 *g*s

-u^2 = 2* g*s

-u^2 = 2*-9.8*1.29

u^2 = 25.284

u = √25.284 = 5.02 m/s

v = u+ gt

t = -u/g = -5.02/-9.8 = 0.51 second

therefore time of ascent = time of descent

so, total time taken to reach ground = 0.51 + 0.51 = 1.02 second