Questions from College Physics

Q: A wire with cross-sectional area A carries a current I

A wire with cross-sectional area A carries a current I. Assuming the wire is ohmic, show that the electric field strength E in the wire is proportional to the current per unit area (I/A) and identify...

Q: In an amusement park rocket ride, cars are suspended from 4

In an amusement park rocket ride, cars are suspended from 4.25 m cables attached to rotating arms at a distance of 6.00 m from the axis of rotation. The cables swing out at a constant angle of 45.0&Ac...

Q: Lars, of mass 82.4 kg, can do work

Lars, of mass 82.4 kg, can do work for about 2.0 min at the rate of 1.0 hp (746 W). How long will it take him to climb three flights of stairs, a vertical height of 12.0 m?

Q: Is it possible to make a heat pump with a coefficient of

Is it possible to make a heat pump with a coefficient of performance equal to 1? Explain.

Q: A voltmeter with a resistance of 670 kΩ is used to measure

A voltmeter with a resistance of 670 kΩ is used to measure the voltage across the 83.0 kΩ resistor in the figure with Problems 79 and 80. What is the voltmeter reading?

Q: A solar cell provides an emf of 0.45 V.

A solar cell provides an emf of 0.45 V. (a) If the cell supplies a constant current of 18.0 mA for 9.0 h, how much electric energy does it supply? (b) What is the power—the rate at which it supplies...

Q: A toy car with a mass of 120 g moves to the

A toy car with a mass of 120 g moves to the right with a speed of 0.75 m/s. A small child drops a 30.0 g piece of clay onto the car. The clay sticks to the car and the car continues to the right. What...

Q: The mass density of diamond (a crystalline form of carbon)

The mass density of diamond (a crystalline form of carbon) is 3500 kg/m3. How many carbon atoms per cubic centimeter are there?

Q: A cylindrical disk has volume 8.97 × 10−3

A cylindrical disk has volume 8.97 × 10−3 m3 and mass 8.16 kg. The disk is floating on the surface of some water with its flat surfaces horizontal. The area of each flat surface is 0.640 m2. (a) What...

Q: An 81 kg student who has just studied matter waves is concerned

An 81 kg student who has just studied matter waves is concerned that he may be diffracted as he walks through a doorway that is 81 cm across and 12 cm thick. (a) If the wavelength of the student must...