Consider two cylindrical conductors made of the same ohmic material. V1 ~E1 I1 ℓ1 r1 b V2 ~E2 I2 ℓ2 r2 b If rho2 = rho1 , r2 = 2 r1 , ℓ2 = 2 ℓ1 , and V2 = V1 , find the ratio R2 R1 of the resistances.

Awheel rotates without friction about a stationary horizontal axis at the center of the wheel. a constant tangential force equal to 82.0 n is applied to the rim of the wheel. the wheel has radius 0.150 m . starting from rest, the wheel has an angular speed of 12.8 rev/s after 3.88 s. what is the moment of inertia of the wheel?

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.

Explain to someone who knows nothing about fossils the study of invertebrate paleontology and how it scientists understand the history of the earth. be sure your explanation contains a minimum of two complete sentences.