In a pulley setup that has a moving pulley,
a. you have to pull the string a greater distance, and it takes more work to lift the mass
b. your work doubles because the pulley moves
c. you have to pull the string a greater distance, but the force needed to lift the mass is cut in half
d. you don't have to pull very much to lift the mass

Explanation:

With a moving pulley you don't have to pull very much to lift the mass, because this pulley distributes better the weight, requiring a lower force to lift than using a simple pulley.

So, basically, in this type of system, the force needed is less, however, to know if is half less or even a minor proportion, we need to use specific values, that's why option C is not the answer, because with the data given, you cannot calculate if the force needed is the half.

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz

the temperature in kelvin of 2.0 dm3 of an ideal gas is doubled and its pressure is increased by a factor of four. what is the final volume of the gas