Answer:
The mass of the ball is 1.360 kilograms.
Explanation:
By Work-Energy Theorem, gravitational potential energy (
), in joules, is the product of weight of the ball (
), in newtons, and height (
), in meters. Please notice that weight is the product of the mass of the ball (
) and gravitational acceleration (
), in meters per square second. Then, the formula for the mass of the ball is:
(1)
If we know that 
, 
and 
, then the mass of the ball is:
The mass of the ball is 1.360 kilograms.
B- lack of control.
the scientists did not have a proper control group.
Answer:
A derived quantities is terms of the 7 base quantities via a system of quantity equations which are called SI derived units.
Explanation: there you go:)
The main requirement for a good conductor of electricity is to have a lot of valence electrons. Valence electrons are the electrons of the outer shells of atoms not bound with other atoms (for example through covalent bounds). These electrons are "free to escape" as soon as an electric field with enough intensity is applied to the material, and therefore these electrons will be free to move in the material producing an electric current.
The resistance of a given conductor depends on its electrical resistivity (
), its length(L) and its cross-sectional area (A), as follows:
In this case, we have 
, 
and 
. So, the total resistance of the wire with length of 138m is:
