Answer:
26 electrons
A neutral iron atom contains 26 protons and 30 neutrons plus 26 electrons in four different shells around the nucleus. As with other transition metals, a variable number of electrons from iron's two outermost shells are available to combine with other elements
Explanation:
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6: Short way: it cannot be 2.5, 3, or 5 because up to 5 seconds it only has positive velocity so it must be moving forwards.
Long Way: Velocity is in m / s, multiply that by time (s) to get m or displacement. From 0->5 you have a triangle under the curve, (1/2)(5)(20) = 50 meters displaced positive, you need to then look when velocity is under the curve and use a similar equation to solve for the area but make the answer negative. Find the point where it equals -50 and that is where it will have returned.
Answer to 6: B
7. I cannot see the problem enough to answer this. Just know if the line is above 0 velocity is positive so it is moving the direction it started, when it goes below 0 velocity is negative so it is moving opposite direction it started.
8. Accelration is change in velocity. Whatever the slope of the velocity graph is acceleration. At t=8 the slope is 0 because it is not going up or down.
Answer to 8: A
Answer:
Explanation:
Let consider that the person hit the ground in the negative direction. The physical model for the impact is modelled after the Impact Theorem:
The impact is:
The force of impact is derived as follows:
Explanation:
let vertical distance from A to C be 
the constraint equation is:
we want to find 
distance can be written as 
which we will find by using Pythagorean theorem h 1 is a constant and can be written as h:
taking derivative w.r.t time we get
given 
which gives us
