Question: An iron nail does not pick up paper clips as a magnet would. What can be concluded about the structure of the iron nail?
Answer: It has domains that are not aligned.
Explanation: because the magnet is not allined its not gonna pick up anything metal cause its not alligned
question answered by
(jacemorris04)
Gamma rays ..........................
Answer:

Explanation:
Since the two charged bodies are symmetric, we can calculate the electric field taking both of them as point charges.
This can be easily seen if we use Gauss's law, 
We take a larger sphere of radius, say r, as the Gaussian surface. Then the electric field due to the charged sphere at a distance r from it's center is given by,

which is the same as that of a point charge.
In our problem the charges being of opposite signs, the electric field will add up. Therefore,

where,
= distance between the center of one sphere to the midpoint (between the 2 spheres)
Answer:
40N
Explanation:
Since both weights are connected to one string, you can say that the tensions above each are equal to each other.
If you do the sum of forces for the 4kg mass, then the tension comes out to 40N (if we take gravity to be 10m/s²). But that seemed too good to be true, so I decided to do the work for the 7kg mass as well [which included finding the normal force (N) and plugging it into the sum of forces for the 7kg mass] to find that it also gives 40N as the answer.
If I were to put my process into steps:
- Write out the sum of Forces for both masses
- Set them equal to each other to find normal force (because this is the only unknown)
- Calculate and compare the two tensions to see if they are equal
*This all seems to line up perfectly, but do let me know if my answer doesn't match up with what you might find to he the answer later on.
Answer:
find acceleration first
a = vf - vi / t
a = 0 - 1.5 / 0.5s (vf is zero)
a = -3 (negative sign indicates that acceleration is decreasing)
so F=ma
F = 35 x -3
F = -105 N (here negative sign indicates that u have to apply a force opposite to the boy's direction i.e from the left or towards the right)
Explanation: