Physics
posted by Harmony on .
A car initially moving at 15 m/s accelerates at 4.5 m/s2 over a distance of 10 m. Find the final velocity?

Let the initial velocity be V1 = 15 m/s and the final velocity be V2 (unknown).
Since F = M a is the accelerating force and the work done is
W = F*X,
K.E. change = (M/2)[V2^2  V1^2] = M*a*X
M cancels out.
V^2^2  V1^2 = 2 a X
Solve for V2.
There is another way to derive the same equation without using the mass and force.
Travel time = T = X/(avg velocity)
T = 2X/(V1 +V2)
V2 V1 = a*T = 2 a X/(V1 + V2)
V2^2  V1^2 = 2 a X 
t=10m/15m.s
=2/3s.
V=u+a¤t
v=(15m/s)+(4.5m/s2)(2/3sec)
v=18m/s