Felipe drives his car at a velocity of 28 m/s. He applies the brake, which slows the vehicle down at a rate of 6.4 m/s2 and causes it to slow to a stop. How long does it take for the car to stop? Round your answer to the nearest tenth.

Animecatgirl Oct 25, 2021

#1**0 **

*Felipe drives his car at a velocity of 28 m/s. He applies the brake, which slows the vehicle down at a rate of 6.4 m/s2 and causes it to slow to a stop. How long does it take for the car to stop? Round your answer to the nearest tenth.*

What we want is for the velocity to equal 0 m/s.

(Initial velocity) minus (acceleration times time) = 0

28 ^{m}/_{sec} – [(6**.**4 ^{m}/_{sec2}) • (t sec)] = 0

Let's subtract (6**.**4 ^{m}/_{sec2}) • (t) from both sides.

28 ^{m}/_{sec} = (6**.**4 ^{m}/_{sec2}) • (t)

Divide both sides by (6**.**4 ^{m}/_{sec2}) This is going to be tricky.

I'm going to call sec^{2} sec-sec so I can cancel one of them

Dividing by a term is the same as multiplying by the inverse of that term.

28 meter 1 sec-sec

––– ––––– • ––– ––––––

1 sec 6**.**4 meter

Cancel units

28 ~~meter~~ 1 sec~~-sec~~ 28 sec

––– ––––– • ––– –––––– = –––––– = 4**.**375 sec, rounds to **4.8 sec**

1 ~~sec~~ 6**.**4 ~~meter~~ 6**.**4

_{.}

Guest Nov 3, 2021