Answer:
Time, I believe. Pretty sure it's time lol
Answer:
There's a video called Drawing Position vs Time Graphs made by MrDGenova that may help you, it's only three minutes long.
Explanation:
Hope that helps, if not, you could tell me what you don't understand and I could try explaining it in further detail.
One of the equations of gravity is this:

Where v = final velocity which is 7m/s
u = initial velocity which is 0 for objects falling from a height
g = acceleration due to gravity and it is approximately 10m/s^2. It's a constant so pretty much remember this number. It's positive since the work being done is caused by gravity (in other words, it's falling down). It can also be negative if the work being down is against gravity (in other words, it's going up)
h = height of object
Substitute for the values and you should have something like this



Potential and kinetic energy are the two types of energy, but they do get separated into subgroups, for which I do not know. Hope that helps.
Answer:
» An electron is lighter than a proton.
<u>explanation</u><u>:</u>

hence it's mass number is zero

hence it's mass number is 4
<u>Therefore</u><u>,</u><u> </u><u>proton</u><u> </u><u>is</u><u> </u><u>heavier</u><u> </u><u>than</u><u> </u><u>electron</u>
» An electron has a small charge magnitude than a proton.
<u>Explanation</u><u>:</u>
An electron has charge of -1 while proton has charge of +2, therefore electron is less deflected by any energetic fields than a proton