Answer:
no where we all stay home
Mean = 43.8 miles per gallon
Standard Deviation = 5.1 miles per gallon
This is a normal distribution and those values ( 38.7 and 48.9 ) are less than one standard deviation away from the mean value:
M - 1 SD = 43.8 - 5.1 = 38.7
M + 1 SD = 43.8 + 5.1 = 48.9
34 % + 34 % = 68 %
Answer:
A ) 68 %
This sounds pretty easy, in fact. The orbital motion can be assumed to be circular and with constant speed. Then, the period is the time to do one revolution. The distance is the length of a revolution. That is 2*pi*R, where R is the distance between the Moon and the Earth (the respective centers to be precise). In summary, it's like a simple motion with constant speed:
v = 2*pi*R/T,
you have R in m and T is days, which multiplied by 86,400 s/day gives T in seconds.
Then v = 2*pi*3.84*10^8/(27.3*86,400) = 1,022.9 m/s ~ 1 km/s (about 3 times the speed of sound :)
For the Earth around the Sun, it would be v = 2*pi*149.5*10^9/(365*86,400)~ 29.8 km/s!
I know it's not in the problem, but it's interesting to know how fast the Earth moves around the Sun! And yet we do not feel it (that's one of the reasons some ancient people thought crazy the Earth not being at the center, there would be such strong winds!)
Taking into account the definition of electron affinity, negative electron affinity means that the anion of the element is more stable than the neutral atom.
Electron affinity is the energy exchanged when a neutral, gaseous atom, and in its ground state, captures an electron to form the anion.
In other words, electronon Affinity is the energy that is given off when a neutral atom in the gaseous state captures an electron to become a negative ion.
The value can be positive or negative. A negative electron affinity means energy must enter in order to bind an electron to the ion, being an endothermic process. If electron affinity is positive, the process is exothermic and occurs spontaneously.
Then, the negative electron affinity (energy is released) occurs when the atoms acquire a more stable configuration when capturing an electron, so the attractive force will predominate. Positive electron affinity (energy is absorbed): occurs when you have to provide energy to the atom to capture the ion.
In summary, negative electron affinity means that the anion of the element is more stable than the neutral atom.
Learn more:
Kinetic energy = 1/2 mv^2
1/2 x 50 x 2.6^2
= 169J