If a ball is rolling down a hill, it has both kinetic and potential energy. The ball has 38 J of potential energy because of its height and 80J of kinetic energy because
of its motion. How much mechanical energy does the ball have

The answer is 118 J :)

Explanation:

38 +80 = 118.

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

a sonic boom is a loud boom that breaks the sound barrier

explanation: