The velocity of a ball as it is thrown up is 20 meters/second. it attains zero velocity after 3.5 seconds. what is the average acceleration of the ball during its upward flight? a. 5.7 meters/second b. 0.57 meters/second c. -0.57 meters/second2 d. -5.7 meters/second2 e. 5.5 meters/second2

The average acceleration is

so the answer is D.

Average acceleration = (change in speed) / (time for the change)

If a ball is thrown upwards at a speed of 20 m/s, and reaches the top of its arc with zero speed after 3.5 seconds, then its average acceleration is

(0 - 20 m/s) / (3.5 s) =

(-20 m/s) / (3.5 s) =

-5.71 m/s² .

Note: This could not be happening on Earth, and there's no planet or other body in our solar system with a gravitational acceleration anywhere near that number.

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