Homework Help: Determinging Acceleration and Distance

1. Dec 12, 2011

C42711

If a rocket-powered sled is accelerated to a speed of 444 m/s in 1.8s, then what is the distance that the sled travels?

So, my given:
vf= 444 m/s
t= 1.8 s

I don 't know what equation to use to find distance. I tried:
d=vi+1/2*at2 , but that didn't work. I just really don't know what equation to use. The answer should be 400m. Any help would be much appreciated.

2. Dec 12, 2011

Delphi51

Knowing only the time and velocities, you must use a formula that has only three quantities - and use it to find the 3rd one. Ideally, you would use a constant accelerated motion formula with d,t,Vi, and Vf. If you can't find that one, use one to find the acceleration and then use d=vi+1/2*at2 to find the distance.

There must be a list of constant accelerated motion formulas in your text book.
The classic version is here: http://en.wikipedia.org/wiki/Equations_of_motion#Equations_of_uniformly_accelerated_linear_motion

3. Dec 12, 2011

PotentialE

have yo tried A = (Vf - Vi) / T?
once you have the acceleration value, the distance formula should work just fine

4. Dec 12, 2011

netgypsy

Most of the time a sled would be accelerated from rest. If it isn't, it tells you the initial velocity.

5. Dec 12, 2011

marcoskids

Need to find acceleration first and then plug its value into the correct equation that you stated.

a = (v-u)/t = (444-0)/1.8 = 247m/s^2

d = vi+1/2*at2

= 0 + 1/2*247*1.8^2

= 400m