Question

A car is traveling at 50 mi/h when the brakes are fully applied, producing a constant deceleration of 44 ft/s2. What is the distance covered before the car comes to a stop? (Give your answers correct to one decimal place.)

Answer 1

help me pleasssssseeeee

Answer 2

i need equation

Answer 3

It doesnt give me an equation.

Answer 4

this is like physics. initial velocity is 50 mi/h, acceleration is -44ft/s^2, d = ?. An equation to use would be Vf^2=Vi + 2ad. Plug in values and go for it! Make sure to get the same units! (mi/h, ft/s^2).

Answer 5

thanks you've been the most help so far... but we are supposed to use the calculus way... but physics seems much more logical

Answer 6

Yea, the calculus way is using derivatives I believe. Acceleration is the derivative of velocity, and velocity is the derivative of position (distance). maybe that will help... :)

Answer 7

but

Answer 8

using this gives me 0 = 50 * 2 * -44 * d

Answer 9

ok so what do you use as your acceleration function

Answer 10

We can use the equation v^2 / 2 = ad. But first we have to change mph to fps.

50*5280/3600 = 73.333

Now 73.333^2/2 = 2688.9 and dividing by 44 gives 61.1 ft for the stopping distance.

Answer 11

she needs to us calculus

Answer 12

exactly...

Answer 13

integrals....

Answer 14

well a(t)=-44

Answer 15

v(t)=-44t+c

50=-44(0)+c

c=50

v(t)=-44t+50

s(t)=-22t^2+50t+c

Answer 16

He's on the right track

Answer 17

at t=0,s(t)=0
0=-22(0)^2+50(0)+c
0=c

s(t)=-22t^2+50t

when the car is at a complete stop v(t)=0

0=-44t+50
-50=-44t
t=25/22

s(25/22)=-22(25/22)^2+50(25/22)

Answer 18

i got 28.40909091

Answer 19

no thats not right.... its 61.1 but i feel like your on the right track...

Answer 20

:(

Answer 21

oh i think i know what it is... the units need to be converted >_<

Answer 22

does it ask for the distance in a specific? i'm guessing it wants it in meters

Answer 23

the velocity needs to be switched to ft/s^2

Answer 24

yep i got 61.056

Answer 25

ok yes...!!!!! FANTASTIC!!!

Answer 26

so using the conversion that feeman did your v(0)=73.3ft/s

Answer 27

and the way you did it i've seen before and understnd.

Answer 28

if you do the same step i did as above but use 73.3ft/sec instead of 50mi/hr you should get the answer

Answer 29

let me know if you can't get it