A hockey puck is hit on a frozen lake and starts moving with a speed of 12.2 m/s. Ex- actly 6.70 s later, its speed is 6.20 m/s. The acceleration of gravity is 9.81 m/s2 . a) What is its average acceleration? Answer in units of m/s2

a=(V-Vo)/t = (6.20-12.2)/6.70=-0.896 m/s^2.

To calculate the average acceleration of the hockey puck, we can use the formula:

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

First, let's calculate the change in velocity:
Change in velocity = final velocity - initial velocity
Change in velocity = 6.20 m/s - 12.2 m/s
Change in velocity = -6.0 m/s

Next, let's calculate the change in time:
Change in time = final time - initial time
Change in time = 6.70 s - 0 s
Change in time = 6.70 s

Now, we can substitute the values into the formula:
Average acceleration = (-6.0 m/s) / (6.70 s)

Dividing -6.0 by 6.70 gives us an average acceleration of approximately -0.895 m/s^2.

So, the average acceleration of the hockey puck is approximately -0.895 m/s^2.