Anonymous

# If the car goes from 0 to 80 mph in six seconds with constant acceceleration, what is that acceceleration?

If the car goes from 0 to 80 mph in six seconds with constant acceceleration, what is that acceceleration?

I asked "2" time but there was a good answer. This is calculus related to physical problem. The question is RIGHT, I did check before posting.

the right answer is 19.55 ft/s^2 ( in the back of the text book)

mph = mile per hour

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Update:

It was written correctly 100% from the college text book

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• raj
Lv 7

80 miles per hour=80*1.47 ft/sec

=117.6 ft /sec

time taken=6 sec

so acceleration=117.6/6=19.55 ft/sec^2

you post the question wrongly and you talk about answer not beingimportant and the steps should be right.

lasttime you had posted the same problem and giventhe speed as 80 kmph

people living in glass houses shouldnot throw stones

• Anonymous

v = u + at

Since u = 0

v = 80 mph

t = 6 s

a = ?

80 mph= a x 6

80 mph = 80/ 60 x 60 miles per second

and 80 miles = 422400 ft

now

422400 /3600 = 6a

4224/36 = 6a

117.3333 = 6a

a = 117.333/6

therefore a = 19.55 ft / second square

I think you're having trouble with the units. The question is stated in several different units and your answer needs to come out in yet another unit. So simply integrating 0 to six and expecting the answer to come out in miles per hour won't do it, becuase the 0 to 6 is in seconds, not hours. And then the answer, to further complicate matters, comes out in feet per second, so when you get your answer in terms of mph, you then have to translate it into feet per second to see if it is right or not.

My suggestion .. use dimensional analysis to translate everything in this question to feet per second, since that's the terms of the answer, then work it out like usual.

a=(v-u)/t

a= (80-0)/6

i cant get 19.55ft/s^2

but thats the formula

just remember what units you are using - you use mph and feet per second in the question - that may confuse you