Author Question: Two wires with the same resistance have the same diameter but different lengths. If wire 1 has ... (Read 43 times)

ec501234 · **on:** Jul 28, 2018

Two wires with the same resistance have the same diameter but different lengths. If wire 1 has length L1 and wire 2 has length L2, how do L1 and L2 compare if wire 1 is made from copper and wire 2 is made from aluminum? The resistivity of copper is 1.7 105 Wm and the resistivity of aluminum is 2.82 105 Wm.
a. L1 = 0.36 L2
c. L1 = 0.60 L2
b. L1 = 2.8 L2
d. L1 = 1.7 L2

Question 2

An initially installed flywheel can store 106 J of kinetic energy when rotating at 300 rad/s. It is replaced by another flywheel of the same size but made of a stronger material. If its mass is the same as that of the original, and it is now capable of achieving a rotational speed of 600 rad/s, what maximum energy can be stored?
a. 40 105 J
c. 10 105 J
b. 20 105 J
d. 5.0 105 J