Question

The brakes on your automobile are capable of creating a deceleration of 5.0 m/s2. If you are going 135 km/h and suddenly see a state trooper, what is the minimum time in which you can get your car under the 75 km/h speed limit

Answer 1

3.33 seconds

Step-by-step explanation:

We can use the velocity formula [ v = u + at ] to solve.

Find the value "u".

135km/h -> 135km*1000m/3600s -> 37.5m/s

Find the value "v".

75km/h -> 75km*1000m/3600s -> 20.83m/s

Keep in mind we are dealing with "deceleration" so when we input 5.0m/s into the formula, it will be a negative value.

Now, find "t" which is the value we aren't given with the values we're given in the question.

20.83 = 37.5 - 5t

-16.67 = -5t

3.33 = t

Best of luck!