Homework Help: Stuck on homework problem

1. Sep 8, 2006

BunDa4Th

I been stuck on this homework problem for about an hour.

A truck covers 40.0 m in 8.25 s while smoothly slowing down to final speed of 2.05 m/s.

(a) Find the truck's original speed.
m/s

(b) Find its acceleration.
m/s2

I was told to use this V^2 = Vo^2 + 2AdeltaX but became lost.

2. Sep 8, 2006

BunDa4Th

Okay, I finally just figure out how to do this and got the answer

a. 7.65m/s and b. -.70

A jet plane lands with a speed of 117 m/s and can accelerate at a maximum rate of -5.80 m/s2 as it comes to rest.

(a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest?
s
(b) Can this plane land on a small tropical island airport where the runway is 0.800 km long?
yes
no
What is the actual minimum distance needed to stop the plane?
km

Can anyone help me with that?

3. Sep 8, 2006

sjmacewan

a) just requires a straight application of $$v=v_0 +a t$$

b) after solving part a, you'll have the time, use that along with velocities (initial and final) in another common kinematics equation, and solve for distance. Then you'll know if .8km is long enough AND you'll have the answer for the 2nd part of b.

4. Sep 9, 2006

BunDa4Th

Thanks for the help and I was able to solve this.