if brakes were applied to a already moving car with a speed of 72 kilometre per hour to reduce it to the speed of 18 kilometre per hour in 10 seconds calculate ​

Acceleration, a = -0.5 m/s²

Explanation:

Given the following data;

Initial velocity = 72 km/h

Final velocity = 18 km/h

Time = 10 seconds

To find the acceleration of the car;

Conversion:

72 km/h to m/s = 72*1000/3600 = 20m/s

18 km/h to m/s = 18*1000/3600 = 5 m/s

In physics, acceleration can be defined as the rate of change of the velocity of an object with respect to time.

This simply means that, acceleration is given by the subtraction of initial velocity from the final velocity all over time.

Hence, if we subtract the initial velocity from the final velocity and divide that by the time, we can calculate an object’s acceleration.

Mathematically, acceleration is given by the equation;

Substituting into the equation;

Acceleration, a = -0.5 m/s²

Therefore, the car is decelerating.

b

explanation:

bc its just b

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