Two wires with the same resistance have the same diameter but ...

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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

[mochi09]

Answer to Question 1

D

Answer to Question 2

A

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TYSM

[Viet Thy]

Excellent