Answer:
u = 4.25 m/s
Step-by-step explanation:
The kinematic expression is as follows:
v² = u² - 2as
where
u = initial velocity
v = final velocity
s = distance
g = acceleration due to gravity .
when he reaches a height of 0.920 m above the floor the final velocity = 0
acceleration due to gravity act opposite the initial direction of motion. So, -9.81 m/s.
v² = u² + 2as
0² - u² = 2 (- 9.81) × 0.920
- u² = 2 × - 9.81 × 0.920
multiply both sides by -1
u² = 2 × 9.81 × 0.920
u² = 18.0504
u = √18.0504
u = 4.2485762321
u = 4.25 m/s