Elements is the simplest form of a pure substance.They cannot be broken down into any thing else ,by either physical or chemical means.In contrasts compounds are pure substances like elements ,they are made up of two or more elements.Just like elements they can be broken down into simpler substances by chemical means,but unlike elements they can only be broken down by chemical means .not both physical and chemical means like elements can.
(I hope that this was helpful.)
If two variables are inversely proportional, then when one increases, the other decreases, and vice versa. If a variable, y, is inversely proportional to a variable, x, then y = k/x, where k is the proportionality constant.
Answer:
1) joule
2) 
3) 
Explanation:
1) Luminosity is the <u>amount of light emitted</u> (measured in Joule) by an object in a unit of<u> time</u> (measured in seconds). Hence in SI units luminosity is expressed as joules per second (
), which is equal to Watts (
).
This amount of light emitted is also called radiated electromagnetic power, and when this is measured in relation with time, the result is also called radiant power emitted by a light-emitting object.
Therefore, if we want to calculate luminosity the Joule as a unit will be used.
2) Work is expressed as force 
multiplied by the distane 
:
Where force has units of 
and distance units of 
.
If we input the units we will have:
This is 1Joule (
) in the SI system, which is also equal to 
3) The formula to calculate the percent error is:
Where:
is the experimental value
is the accepted value
This is the percent error
The answer is true. Gravity is the force that keeps us all on the ground.
