1. A car is coasting backwards downhill at a speed of 3.0 m/s when the driver gets the engine started. After 2.5 s, the car is moving uphill at 4.5 m/s. Assuming that uphill is positive direction, what is the car’s average acceleration?

acceleration=(4.5-(-3.0))/2.5

To find the car's average acceleration, we can use the equation:

acceleration = (final velocity - initial velocity) / time

Given:
Initial velocity (u) = -3.0 m/s (downhill)
Final velocity (v) = 4.5 m/s (uphill)
Time (t) = 2.5 s

Substituting the values into the formula:

acceleration = (4.5 m/s - (-3.0 m/s)) / 2.5 s

Simplifying the equation:

acceleration = (4.5 m/s + 3.0 m/s) / 2.5 s

acceleration = 7.5 m/s / 2.5 s

acceleration = 3 m/s²

Therefore, the car's average acceleration is 3 m/s².

To find the car's average acceleration, we need to use the formula:

average acceleration = (change in velocity) / (change in time)

First, we need to find the change in velocity.
The initial velocity is 3.0 m/s (coasting backwards downhill) and the final velocity is 4.5 m/s (moving uphill).

Therefore, the change in velocity = final velocity - initial velocity
change in velocity = 4.5 m/s - (-3.0 m/s)
change in velocity = 7.5 m/s

Next, we need to find the change in time. The time given is 2.5 s.

Now we can calculate the average acceleration:
average acceleration = (change in velocity) / (change in time)
average acceleration = 7.5 m/s / 2.5 s
average acceleration = 3.0 m/s²

So, the car's average acceleration is 3.0 m/s².

4.5-3/2.5=.6