I don't think that 4m has anything to do with the problem.
anyway. here.
A___________________B_______C
where A is the point that the train was released.
B is where the wheel started to stick
C is where it stopped
From A to B, v=2.5m/s, it takes 2s to go A to B so t=2
AB= v*t = 2.5 * 2 = 5m
The train comes to a stop 7.7 m from the point at which it was released so AC=7.7m
then BC= AC-AB = 7.7-5 = 2.7m
now consider BC
v^2=u^2+2as
where u is initial speed, in this case is 2.5m/s
v is final speed, train stop at C so final speed=0, so v=0
a is acceleration
s is displacement, which is BC=2.7m
substitute all the number into equation, we have
0^2 = 2.5^2 + 2*a*2.7
0 = 6.25 + 5.4a
a = -6.25/5.4 = -1.157
so acceleration is -1.157m/(s^2)
First, we need to find the number of protons, which is the total mass divided by the mass of one proton:
![N= \frac{m}{m_p}= \frac{1.0 kg}{1.67 \cdot 10^{-27} kg}=6.0 \cdot 10^{26}](https://tex.z-dn.net/?f=N%3D%20%5Cfrac%7Bm%7D%7Bm_p%7D%3D%20%5Cfrac%7B1.0%20kg%7D%7B1.67%20%5Ccdot%2010%5E%7B-27%7D%20kg%7D%3D6.0%20%5Ccdot%2010%5E%7B26%7D%20%20%20)
protons
Then, the total charge is the number of protons times the charge of a single proton:
Chaff has also written about his book of Mormon that is not true to say this but it doesn't have the
A. 314 because when you use the formula for the GPE ; GPE=MGH or means mass times gravity time height (4x8x9.8) and thats equivalent to 313.6 which rounds up to 314. Hope it helps