Answer:
The resistance must be 6.67
Solution:
Resistance, 
Resistance, 
For the current to be the same when the switch is open or closed, the resistances must be connected in parallel as current is distributed in parallel with the same voltage across the circuit:
Thus in parallel:



Answer:
change in mass = 2.41*10^{8}kg
Explanation:
The change in the mass can be computed by using the relation
(1)
That is, the energy liberated comes from the mass of the nuclear fuel. The energy generated in one year is

Hence, by replacing in the equation (1) you have (c=3*10^{8}m/s)

HOPE THIS HELPS!!
Answer:
C
Explanation:
Because this same question was on my test last week and I got it correct
Answer:
50 N
Explanation:
Efficiency of a machine can't be more than 1, so I assume you mean 40%. (Remember, efficiency and mechanical advantage are not the same).
Efficiency is the ratio of work out of a system to the work in to the system.
e = Wout / Win
Work is force times distance, so:
e = (Fout × Dout) / (Fin × Din)
Rearranging:
Fin = (Fout × Dout) / (e × Din)
Fin = (Fout / e) × (Dout / Din)
Fin = (Fout / e) / (Din / Dout)
We know that e = 0.40, and Fout = 120 N. Since there are 6 pulleys, we also know that Din/Dout = 6.
F = (120 N / 0.4) / 6
F = 50 N