Question

A car slow down at -5.00 m/s2 until it comes to a stop after traveling 15.0 m. What was the initial speed of the car? (Unit=m/s)

Answer 1

Answer:

12.25 m/s

Explanation:

If a car slows down at -5 m/s2 and it comes to a stop after traveling 15 m we just have to use the next formula:

$Vf^{2} =Vo^{2} +2ad$

Now we know that the final velocity is 0, so by inserting our data into the formula it would look like this:

$Vf^{2} =Vo^{2} +2ad$

$0 =Vo^{2} +2(-5m/s^{2})(15m)$

$-Vo^{2}= -150m^{2}/s^{2}$

$Vo^{2}= 150m^{2}/s^{2}$

$Vo= \sqrt{150m^{2}/s^{2}}$

$Vo= 12.25m/s$

Answer 2

Good formula to remember!

V_F^2 = V_0^2 + 2 * a * d

V_F = final speed
V_0 = initial speed

0^2 = V_0^2 + 2*(-5)*15 = V_0^2 -150,

V_0 = sqrt(150) = 12.25 m/s