<u>Answer
</u>
D. Salt water is denser than freshwater.
<u>Explanation</u>
A boat is able to float on water because it experiences an upthrust upwards.
The magnitude of the upthrust depends on the density of the liquid.
When the liquid is denser the boat will experience a great upthrust as compared to when in a less dense liquid.
If the boat sinks lower in the freshwater than in salty water, then Salt water is more dense than freshwater.
That is the Sigma Symbol. It’s the addition of a sequence of numbers; the result is the sum of the total. if numbers are added sequentially from left to right, any intermediate result is a partial sum, prefix sum, or running total of the summation
Answer:
F=248.5W N
Explanation:
Newton's 2nd Law tells us that F=ma. We will use their averages always. The average acceleration the tennis ball experimented is, by definition:

Since we start counting at 0s and the ball departs from rest, this is just 
So we can write:

Where in the last step we have just multiplied and divided by g, the acceleration of gravity. This allows us to introduce the weight of the ball W since W=gm, so we have:

Substituting our values:

Where the average force exerted has been written it terms of the tennis ball's weight W.