Answer:
7.07 s
69.3 m/s
Explanation:
Taking the negative direction to be down and the positive direction to be up:
We have 3 variables in the y-direction and can solve for time.
- v₀ = 0 m/s
- a = -9/8 m/s²
- Δy = -245 m
- t = ?
Use this kinematics equation to solve for time.
- -245 = 1/2(-9.8)t²
- -245 = -4.9t²
- t² = 50
- t = 7.07106781187
It will take the ball 7.07 s to reach the ground.
We can solve for final velocity using the same variables in the y-direction:
- v₀ = 0 m/s
- a = -9/8 m/s²
- Δy = -245 m
- v = ?
Use this kinematics equation to solve for final velocity.
- v² = v₀² + 2aΔx
- v² = 2(-9.8)(-245)
- v² = 4802
- v = 69.2964645563
The ball will be traveling at a speed of 69.3 m/s at the instant before it reaches the ground.
