Question

a car traveling at a speed of 90 k/h comes to a complete to stop in 5 s when the brakes are passed calculate the acceleration and justify your answer

Answer 1

Answer:

• The Acceleration is -5m/s².

Explanation:

Initial velocity (u) = 90km/h

[1km = 1000m and 1h = 3600s]

• ➺ u = 90 × 1000m/3600s
• ➺ u = 25m/s

Time taken (t) = 5s

Final velocity (v) should be 0m/s as brakes are applied to stop the car.

• ➺ v = 0m/s

As we know that,

• The rate of change in velocity is called Acceleration.

So,

• ➺ (v - u)/t = a
• ➺ (0 - 25m/s)/5s = a
• ➺ - 25m/s / 5s = a
• ➺ a = -5m/s²

Hence, The Acceleration is -5m/s².

We can say that, The retardation is 5m/s².