A 2.0-m lamp cord leads from the 110-V outlet to a lamp having a 75-W lightbulb. The cord consists of two insulated parallel wires 8.0 mm apart and held together by the insulation. One wire carries the current into the bulb, and the other carries it out.

1. What is the magnitude of the magnetic field the cord produces midway between the two wires? μT

2. What is the magnitude of the magnetic field the cord produces 2.0 mm from one of the wires in the same plane in which the two wires lie? μT

3. Compare the field between the two wires with Earth’s magnetic field (0.5×10^−4 T). Give your answer as B/BEarth.

4. Compare the field between 2.0 mm from one of the wires in the same plane in which the two wires lie with Earth’s magnetic field?

5. What magnetic force do the two wires exert on one another? μN

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒

Amira pulls a 3 pound wagon 4 feet. how much work has she done?

An athlete is holding 24 lb of weights at a height of 6 inches above the stack as shown. to lower the weights, she applies a constant force of 5 lb to the handle. determine the velocity of the weights immediately before they hit the stack.