Answer:
Four fundamental forces are gravitational, electromagnetic, strong, and weak.
Explanation:
The gravitational and electromagnetic interactions, which produce significant long-range forces whose effects can be seen directly in everyday life and the strong and weak interactions, which produce forces at minuscule, subatomic distances and govern nuclear interactions.
<span>The correct frequency when you tune a guitar is
when you hear the right tune in your own hearing and standard. The measure
frequency of a guitar string is when you measure the tune of the string
correctly. This is not the same because manual tuning is affected by many
factors.</span>
Answer:

Explanation:
P = Power = 50 kW
n = Number of photons per second
h = Planck's constant = 
= Frequency = 781 kHz
r = Distance at which the photon intensity is i = 1 photon/m²
Power is given by

Photon intensity is given by

The distance is 
Answer:
V = 3.54 m/s
Explanation:
Using the conservation of energy:

so:

where w is te weigh of kelly, h the distance that kelly decends, m is the mass of kelly and V the velocity in the lowest position.
So, the mass of kelly is:
m = 425N/9.8 = 43.36 Kg
and h is:
h = 1m-0.36m =0.64m
then, replacing values, we get:

Solving for v:
V = 3.54 m/s
Answer:
A - elastic since many other fast food items could be considered close substitutes.
Explanation:
The price elasticity of demand is how much the demand of the Big Macs will change due to a 1% change in price. Should the elasticity be greater than 1, the Big Macs will be elastic. Should it be less than 1, the Big Macs are inelastic.
Demand elasticity is calculated as the percentage change in quantity demanded divided by a percentage change in price.
Since Big Macs are (i) a luxury good, and (ii) have close substitutes (other burgers available at McDonalds and other fast food stores), we will say their elasticity is greater than 1.
This means that the demand of Big Macs will change due to a 1% increase in price due to the presence of close substitutes.