Question

a car traveling at 28 m/s slows down at a constant rate for 4 seconds until it stops. what is its acceleration?

Answer 1

We are given the following conditions:
$v_{0} = 28m/s t = 4s v_{f} = 0m/s$

Since we are told it slows down at a constant rate, we know we are dealing with uniformed accelerated motion, or UAM for short.

So we look at our kinematics equation that contains the given variables.

$v_f = v_0 + at$

This contains our target variable and our initial conditions. Plug and chug, we get:

$(0m/s) = (28m/s) + a(4s) -28m/s = (4s)*a a = -7m/s^2$

Thus the answer is:

a = -7m/s^2

Hope this helps!