PH 222 Recitation Homework Spring 2018

Chapter 04 (due week 03 recitation)

The angular velocity of a variable-speed motor is ω = (20 - 0.5t²) rad/s, where t is greater than or equal to zero and measured in seconds. (a) At what time does the motor reverse direction? (b) Through what angle does the motor turn between t = 0 s and the instant at which it reverses direction?

Chapter 08 (due week 04 recitation)

A car starts from rest and moves around a circular, horizontal, level track of radius 30.0 m. Its speed increases at the constant rate of 0.500 m/s². (a) What is the magnitude of the net acceleration 15.0 s later? (b) What angle does the net acceleration make with the car's velocity at this time?

Chapter 12 (due week 05 recitation)

A uniform solid sphere rolls without slipping along a flat, level, frictionless horizontal surface. It then rolls up a frictionless inclined plane. The angle of incline is θ. Its speed is momentarily zero after it has rolled a distance d along the ramp. Determine its speed at the base of the inclined plane in terms of θ, d and/or g.

Chapter 15 (due week 06 recitation)

A 2.00-kg block hangs vertically from a spring. The block-spring system is in static equilibrium. A 300-g wad of putty is stuck to the block and when the block-spring-putty system reaches static equilibrium, the spring has stretched 2.00 cm further than it had before the putty was added. What is the spring constant of the spring?

Chapter 16 (due week 07 recitation)

You are standing at a distance d from a speaker that emits sound waves in all directions. You walk 25.0 m toward the speaker and observe that the intensity of the sound has doubled. Determine the distance d. Ignore the fact that the sound waves will reflect off the ground and other nearby objects.

Chapter 17 (due week 08 recitation)

Two identical speakers separated by distance Δx each emit sound waves of wavelength λ and amplitude A along the x-axis. What is the minimum value of the ratio Δx/λ for which the amplitude of their superposition is also A?

Chapter 33 (due week 09 recitation)

A diffraction grating with 1000 slits/cm is oriented parallel to the y-axis and its center is located on the x-axis at x = -5.00 m. A source of light of wavelength 650 nm is located on the x-axis at x = -125 m. At how many locations does constructive interference occur on the y-axis? Use the symbol N for the number of locations.

Chapter 34 (due week 10 recitation)

A point source of light is located 80.0 cm below the surface of a body of fresh water. What is the diameter of the circle at the surface through which light emerges from the water?