# The air temperature was 84.90°F during a thunderstorm, and thunder was timed 3.08 s after lightning was seen. How many feet away was the lightning strike?

Please show work. Due on October 14 2016

• The air temperature was 84.90°F during a thunderstorm, and thunder was timed 3.08 s after lightning was seen. How many feet away was the lightning strike?

• A sound wave with a frequency of 480 Hz moves with a velocity of 420 m/s. What is the distance from one condensation to the next?

• You see condensed steam expelled from a ship’s whistle 8.33 s before you hear the sound. If the air temperature is 26.5°C, how many meters are you from the ship?

• A ship at sea sounds a whistle blast, and an echo returns from the coastal land 18.6 s later. How many km is it to the coastal land if the air temperature is 13.7°C?

• (Has two parts)

vair = 331 m/s

vrail = 5,940 m/s

Compare the distance traveled in 9.04 s as a given sound moves through

(a) air at 0°C and

___ km

(b) a steel rail.

____ km

6.)( has four parts) The following sound waves have what velocity?

(a) Middle C, f = 256 Hz and λ = 1.34 m

(b) The note A, f = 440.0 Hz and λ = 78.0 cm-

(c) A siren with f = 736.0 Hz and λ = 46.6 cm

(d) A note from a stereo with f = 2,600.0 Hz and λ = 13.2 cm

7.)(has two parts) A water wave has a frequency of 5.0 Hz and a wavelength of 5.0 m.

(a) What is the period of these waves? Answer must be in s

(b) What is the wave velocity? Answer must be in m/s

8.) Water waves are observed to pass under a bridge at a rate of one complete wave every 4.6 s.

(a) What is the period of these waves answer must be in  s

(b) What is the frequency? Answer must be in  Hz

9.) The lower frequency limit of hearing for a particular human being is 25.0 Hz. What is the corresponding wavelength for this frequency if the air temperature is 18.2°C? λ =  m

10.) The distance between the center of a condensation and the center of an adjacent

rarefaction is 76.30 cm. If the frequency is 218.5 Hz, how fast are these waves moving?

___ × 10 cm/s

11.)  A small radio operates on 120.0 V and has a resistance of 95.0 Ω. At what rate does the radio use electric energy?

12.)  A wire carries a current of 1.8 A. At what rate is the charge flowing?answer in  C/s

13.)  (has three parts) An average-sized home refrigeration unit has a 1/5−hp fan motor for blowing air over the inside cooling coils, a 1/3−hp fan motor for blowing air over the outside condenser coils, and a 2.00−hp compressor motor.

(a) All three motors use electric energy at what rate? Answer must be in Energy =

(b) If electricity costs \$0.15/kWh, what is the cost of running the unit per hour? answer must be cost = \$

(c) What is the cost for running the unit 12 hours a day for a 30−day month? (Round final answer to the nearest cent.) answer must be cost = \$

14.)  Is it possible for two people to simultaneously operate 1,800 W hair dryers on the same 120 V circuit without tripping a 10 A circuit breaker?

Explain.

Each hair dryer draws ___ A of current, so two such devices  cause a 10−A breaker to trip.

15.) An electric current through a wire is 7.68 C every 2.75 s. What is the magnitude of this current? answer in a

16.) ( has two parts) A step-up transformer has a primary coil with 125 loops and a secondary coil with 2,250 loops. If the primary coil is supplied with a household current of 120 V and 25 A,

(a) what voltage is produced in the secondary circuit? Answer must be in V

(b) What current flows in the secondary circuit? Answer must be in  A

17.)  A rubber balloon has become negatively charged from being rubbed with a wool cloth, and the charge is measured as 1.00 × 10−14 C. According to this charge, the balloon contains an excess of how many electrons? Answer n __ x 10 ^__

17.) There is a current of 0.86 A through a lightbulb in a 12 V circuit. What is the resistance of this lightbulb?  Answer in Ω

18.)  An inflated rubber balloon is rubbed with a wool cloth until an excess of 1.00 × 1010 electrons is on the balloon. What is the magnitude of the charge on the balloon? __ x10 ^___ C

19.) Two 45.0−Ω lightbulbs are connected in a 24.0−V series circuit. What is the power of One bulb (as described above) in a simple circuit?

P = _ W

One bulb in a pair of identical bulbs (as described above) connected in a 120.0 V series circuit?

P = ____ W

Thus, two lamps connected in a series circuit, as compared to one lamp in a simple circuit, increases decreases the current by one fourth one half three fourths and decreases increases the voltage by one fourth one half three fourths  , resulting in  the power for each lamp. (choose one from the underlined)

20.)  Round final answer to the nearest cent. A 2,750-W hair dryer is operated on a 120-V circuit for 23 min. If electricity costs \$0.22/kWh, what was the cost of using the blow dryer? cost = \$

21.) ( has two parts) One rubber balloon with a negative charge of 5.60 × 10−14 C is suspended by a string and hangs 2.40 cm from a second rubber balloon with a negative charge of 2.40 × 10−12 C.

(a) What is the direction of the force between the balloons?

( choose one from the underlined)  Repulsive, neutral attractive

(b) What is the magnitude of the force?

___ × 10^__ N