2- What is the kinetic energy in (N. m) and Joules of a 4Kg bowling ball rolling down a bowling lane at 10 m/s? compare this energy with that of a 250g baseball traveling 50

m/s. which object would hurt more if it hit you (i. e., which object has the greater kinetic

energy)?

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Recall the equation for kinetic energy:

m = mass (Kg)

v = velocity (m/s)

KE = kinetic energy (Nm or J)

We can find the kinetic energy for both the bowling ball and baseball:

Bowling ball:

Baseball:

Since 312.5 J > 200 J, the BASEBALL has the greater kinetic energy. Thus, it would exert a greater impact force than the bowling ball, so it would hurt more.

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