Which of the following best explains why electrical wires are usually covered with plastic or rubber

A thin copper rod that is 1.0 m long and has a mass of 0.050 kg is in a magnetic field of 0.10 t. What minimum current in the rod is needed in order for the magnetic force to cancel the weight of the rod?

Where do plants get energy to live and grow?

A fire engine must lift 30 kg of water a vertical distance of 20 m each second. What is the amount of power needed for the water pump for this fire hose?

In order for a solution to form a) one substance must dissolve in another. b) a solid must dissolve in liquid. c) the solvent must be water. d) a gas must dissolve in a liquid.

Low-grade uranium ore contains a fraction of a percent (by weight) of uranium; very high-grade ore (as is found in some deposits in Canada) can contain up to 20% uranium. A) If energy is extracted from uranium by fission of 235U (0.

What process is used when the sun transfers light to plants A. conduction B. radiation C. convection D. all of these

Which wave characteristic has the unit hertz

A stretched spring has 5184 J of elastic potential energy and a spring constant of 16,200 N/m. What is the displacement of the spring?

A block of mass 1.3 kg is resting at the base of a frictionless ramp. A bullet of mass 50 g is traveling parallel to the ramp surface at 250 m/s. It collides with the block, enters it, and exits the other side at 100 m/s.

Metals are good thermal conductors - that is, when there is a temperature difference across their ends, they transfer energy very efficiently from the higher temperature end to the lower temperature end.