If the mechanical advantage of a simple machine is 4, then which of the following statements is true? A. The output force is 4 times the input force
B. The input force 4 times the output force
C. The resistance force is 4 times the effort work.
D. The efficiency is 4%

Idon’t quite understand this problem

(a) calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 10.0 g. silver has 47 electrons per atom, and its molar mass is 107.87 g/mol. (b) imagine adding electrons to the pin until the negative charge has the very large value 1.00 mc. how many electrons are added for every 109 electrons already present

Find the magnetic field a distance r from the center of a long wire that has radius a and carries a uniform current per unit area j in the positive z direction.