Work with your units:
1 watt-hour = 1 (joule/second) · (hour) = 1 (joule-hour / second)
(1 joule-hour/sec) · (3600 sec/hour) = 3600 joules
So 1 watt-hour = 3,600 joules
Answer:
Part a) 
Part b) 
Explanation:
Part a) what is its frequency, in rev/s
we have that
An old-fashioned LP record rotates at 33 1/3 RPM
so

Convert mixed number to an improper fraction

Remember that

Convert rev/min to rev/sec

Simplify

Part b) what is it period, in seconds
we know that
The period is the reciprocal of the frequency
therefore
the frequency is

4 atoms
Explanation:
On the product side, we expect to find 4 atoms of the product.
An atom is the smallest indivisible particle that takes part in a chemical reaction.
An element is a distinct substance that cannot be split-up into simpler substances. Such substances consist of only one kind of atom.
In this reaction we have:
2 elements: Mg O
on the reactant side:
We have two moles of Mg: 2 atoms of Mg
1 mole of oxygen gas: 2 atoms of O
total atoms: 4 atoms
According to the law of conservation of matter "in a chemical reaction, matter is neither created nor destroyed".
We expect to find 4 atoms of products which is MgO on the product side.
2Mg + O₂ → 2MgO + heat
Learn more:
Conservation of matter brainly.com/question/2190120
#learnwithBrainly
On December 1, 1913, Henry Ford installs the first moving assembly line for the mass production of an entire automobile. His innovation reduced the time it took to build a car from more than 12 hours to one hour and 33 minutes.
The electric force is small in comparison because charges are VERY small but the
gravitational force has to do with the mass of the Earth and Moon.