Question

A brake is applied to a car traveling at a constant speed of 90 km/h. If the deceleration a caused by the braking action is 5 m/s2, find the time and distance before the car stops.

Answer 1

Answer:

5 seconds

62.5 meters

Step-by-step explanation:

90 km/h = 25 m/s

To find the time elapsed from hitting the brakes to the car completely stopping, apply the following equation:

$v=v_0-at$

Where 'v' is the final velocity of 0 m/s and 'v0' is the initial velocity of 25 m/s:

$0=25-5t\\t=5\ s$

The car travels for 5 seconds before stopping.

The distance traveled by the car is given by:

$\Delta S= v_0t-\frac{at^2}{2}\\ \Delta S= 25*5-\frac{5*5^2}{2}\\\Delta S= 62.5\ m$

The car travels for 62.5 meters before stopping.