A major league pitcher can throw a baseball with a kinetic energy of 150 J. How much work must the pitcher do to the ball to give it that much KE? A.) 150 J

B.) 0 J

C.) can't tell without knowing the mass of the ball

D.) 75 J

A= 150 J

Explanation:

Kinetic energy is the energy of an object in motion.

The formula for kinetic energy is ;

K.E = 1/2 * m *v²  where m is mass and v is velocity

Work done is equal to change in kinetic energy

W= Δ K.E

Given that K.E = 150 J

Taking that the ball was stationary before it was thrown, this makes its initial kinetic energy to be 0 J so the work done will be

W=  Δ K.E

W= 150 - 0

W= 150 J

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