find the distance covered before applying brakes ? follow my intrro
Answers
Answer:
Hint- In this question, first we will determine the distance travelled by car during reaction time, then we will proceed further by using the third equation of motion to find the distance covered by the car in the deceleration period. We will consider the final velocity 0 as the will finally come to halt.
Formula used- Distance=speed×time,v2−u2=2as
Complete step-by-step answer:
Given that
Initial velocity =u=54km/hr=54×518m/s=15m/s
Reaction time=t=0.2sec
Final velocity =v=0m/s
Deceleration 6.0 m/s2
Now, Distance travelled by car during reaction time:
⇒Distance=speed×time⇒Distance=15m/s×0.2s⇒Distance=3m
As we know that the third equation of motion gives the final velocity of an object under uniform acceleration given the distance traveled and an initial velocity:
v2−u2=2as
Substitute the value of v, u and a in this equation, so we have
⇒02−152=2(−6)s⇒−225=−12s⇒s=−225−12⇒s=22512=18.75m
Therefore, the total distance travelled by the driver after he sees the need to put the brakes ON
=18.75+3=21.75m
Hence, distance traveled by the car after he sees the need to put the brakes on is 21.75m