A car slows to a stop with an average acceleration of - 3.0 m/s2. How long will it take to slow the car from 15 m/s to a position of rest?

To find the time it takes for the car to slow from 15 m/s to rest, we can use the equation:

v^2 = u^2 + 2as

Where:
v = final velocity (0 m/s in this case, as the car comes to rest)
u = initial velocity (15 m/s in this case)
a = acceleration (-3.0 m/s^2 in this case)
s = distance

Rearranging the equation, we have:

0^2 = 15^2 + 2(-3.0)s

Simplifying further:

0 = 225 - 6s

Rearranging the equation once more:

6s = 225

Dividing both sides by 6:

s = 37.5 m

So, the distance the car needs to travel to come to rest is 37.5 meters.

Now, we can use the equation for average acceleration to find the time:

a = (v - u) / t

Rearranging the equation, we have:

t = (v - u) / a

Substituting in the given values:

t = (0 - 15) / -3.0

Calculating further:

t = -15 / -3.0

t = 5 seconds

Therefore, it will take 5 seconds for the car to slow from 15 m/s to a position of rest.

To answer this question, we need to use the equation for acceleration:

acceleration = change in velocity / change in time

Given that the average acceleration is -3.0 m/s^2 and the initial velocity is 15 m/s, we can calculate the change in velocity by subtracting the final velocity (which is 0 m/s) from the initial velocity:

change in velocity = final velocity - initial velocity
change in velocity = 0 m/s - 15 m/s
change in velocity = -15 m/s

Now we can rearrange the equation to solve for change in time:

acceleration = change in velocity / change in time

Substituting the values we have:

-3.0 m/s^2 = -15 m/s / change in time

To isolate the change in time, we can multiply both sides of the equation by change in time:

-3.0 m/s^2 * change in time = -15 m/s

We can then solve for the change in time by dividing both sides of the equation by -3.0 m/s^2:

change in time = -15 m/s / -3.0 m/s^2
change in time = 5 seconds

Therefore, it will take 5 seconds to slow the car from 15 m/s to rest.