Answer:
a) 
Now we can replace the velocity for t=1.75 s

For t = 3.0 s we have:

b) 
And we can find the positions for the two times required like this:
And now we can replace and we got:

Explanation:
The particle position is given by:

Part a
In order to find the velocity we need to take the first derivate for the position function like this:

Now we can replace the velocity for t=1.75 s

For t = 3.0 s we have:

Part b
For this case we can find the average velocity with the following formula:

And we can find the positions for the two times required like this:
And now we can replace and we got:

Answer:
The answer to your question is letter B
Explanation:
Data
Order from fastest to slowest speed
58 72 55 65 70 81 66
The fastest is 81, then, 72, 70, then, 66, 65 finally 58 and 55
The correct order
81 mi/h, 72 mi/h, 70 mi/h, 66 mi/h, 65 mi/h, 58 mi/h, 55 mi/h
The other options are from slowest to fastest or a different order.
Answer:
the ball is rolling 7m/s
Explanation:
Formula for kinetic energy: 1/2mv²
K = 1/2mv²
98 = 1/2(4)v²
98 = 2v²
49 = v²
√49 = v
7 = v
I believe the correct answer is d. thermosphere.