A Jamaican Bobsled team hits the brakes on their sled so that decelerates at a uniform rate of 0.43 m/s^2. How long does it take to stop if it travels 86.5 m before stopping?

20.05 seconds

Explanation:

Given that:

v² = u² + 2as

v = final velocity

u = initial velocity

a = acceleration

s = distance

a = negative acceleration = - 0.43

s = distance = 86.5

v = 0

0 - 2(0.43)(86.5) = u²

74.39 = v²

U = sqrt(74.39)

U = 8.6249

From ;

t = Time in seconds

t = (v - u) / a

t = (0 - 8.6249) / - 0.43

t = 20.057

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