What is the velocity of a 800 kg roller coaster car at a height of zero if its mechanical energy at the highest point is 165,800 J? A. 14.4 m/s
B. 0 m/s
C. 414.5 m/s
D. 20.4 m/s

B. 0 m/s

Explanation:

Given parameters:

Mass of roller coaster  = 800kg

Height  = 0

Mechanical energy at highest point  = 165800J

Unknown:

Velocity  = ?

Solution:

The mechanical energy is the sum of the potential and kinetic energy within a give system.

At the highest point, the velocity of the roller coaster will be zero.

All the kinetic energy would have been transformed into potential energy.

So, the velocity is 0m/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