why is it important to keep the temperature and the amount of water the same when testing surface area?

The temperature and the amount of water need to be kept the same so that the only variable that changes is the surface area. If you allow the temperature and/or the amount of water to change too, you will not know which variable is causing the changes that you observe.

Explanation:

So you do not have different changes in temperature, that can result to changes and speed and the final estimate

Explanation:

This is what i typed and i got it correct on edge 2020

there are no contact forces mentioned on the list of choices that you've provided.

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m