Answer:
The sponge must go
deep
Explanation:
If F = 6360 N, then it is required to find how deep can an object with this force hitting on a sponge get.
We know that, F = mgh
m is mass
g is acceleration due to gravity

So, the sponge must go
deep.
I believe this would be an example of Mary's velocity. We have her speed and direction which is all you need to find velocity.
Answer:
I feel like to demonstrate you would use an elastic band as the material. You obviously have to put force in order to see how far it stretches. From this you can also find about its resistance and durability
Also you have to make sure the distance between the two hands are equal as you want an accurate result.
For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.