katelyn throws a rock which travels 34 m above her hand before it starts to fall. what is the vertical velocity of the rock when it leaves her hand?

25.8 m/s

Explanation:

Initial Velocity (u) =?

Final velocity before it starts to fall ; v = 0

Distance (S) = 34 meters

Using the relation :

v² = u² + 2aS

a = - 9.8 m/s²

0 = u² + 2(-9.8)(34)

0 = u² - 666.4

u² = 666.4

u = √666.4

u = 25.814724

Hence, vertical velocity when the rock leaves her hand is 25.8 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s