GEAS 03 - Physics 2

1. A car is traveling at 20 m/s away from a stationary observer. If the car’s horn emits a frequency of 600 Hz, what frequency will the observer hear? (Use v = 340 m/s for the speed of sound.)

• (34/36)(600 Hz)

• (34/32)(600 Hz)

• (36/34)(600 Hz)

• (32/34)(600 Hz)

2. An observer is 2 m from a source of sound waves. By how much will the sound level decrease if the observer moves to a distance of 20 m?

• 1 dB

• 18 dB

• 10 dB

• 20 dB

Answer explanation

Distance² is INVERSELY PROPORTIONAL to Intensity

from 2m to 20m, it increased by a factor of 10.

Distance 10² -----> Intensity 1 / 100

I = 10 log (1 / 100) ----> 20 dB

3. A sound wave traveling through water has a frequency of 500 Hz and a wavelength of 3 m. How fast does sound travel through water in m/s?

• 1000

• 1500

• 950

• 750

4. A sound wave with a frequency of 343 Hz travels through the air. What is its wavelength?

• 1 m

• 0.1 m

• 1.2 m

• 5 m

A transverse wave on a long horizontal rope with a wavelength of 8 m travels at 2 m/s. At t = 0, a particular point on the rope has a vertical displacement of +A, where A is the amplitude of the wave. At what time will the vertical displacement of this same point on the rope be –A ?

• t=s/8

• t=s/2

• t=2s

• t=s/4

6. A horizontal rope with linear mass density μ = 0.5 kg/m has a tension of 50 N. The nonattached end is oscillated vertically with a frequency of 2 Hz. What is the wavelength of the resulting wave?

• 0.05 m

• 0.5 m

• 5 m

• 50 m

7. A rope of length 5 m is stretched to a tension of 80 N. If its mass is 1 kg, at what speed would a 10 Hz transverse wave travel down the string?

• 2 m/s

• 4 m/s

• 20 m/s

• 40 m/s

8. An object of height 4 cm is placed 30 cm in front of a concave mirror whose focal length is 10 cm. What is the height of the image?

• 4 cm, upright

• 4 cm, inverted

• 2 cm, upright

• 2 cm, inverted

9. When green light (wavelength = 500 nm in air) travels through diamond (refractive index = 2.4), what is its wavelength?

• 208 nm

• 500 nm

• 357 nm

• 700 nm

10. 10. An object is placed 60 cm in front of a concave spherical mirror whose focal length is 40 cm. Which of the following best describes the image?

• Image is virtual, 24 cm away

• Image is real, 24 cm away

• Image is virtual, 120 cm away

• Image is real, 120 cm away