A mirror faces a cliff located some distance away. Mounted on the cliff is a second mirror, directly opposite the first mirror and facing toward it. A gun is fired very close to the first mirror. The speed of sound is 342 m/s. How many times does the flash of the gunshot travel the round-trip distance between the mirrors before the echo of the gunshot is heard? N = i

As a racing car zooms by you, its pitch (frequency) decreases by 20%. If the speed ofsound is 345 m/s, how fast is the car travelling?

On a day when the speed of sound in air is 340 m/s, a lightning bolt is observed and the resultant thunderclap is heard 2 seconds afterwards. About how far away was the lightning bolt?

A string with a 10-gram decoration on the end is attached to the rear-view mirror of your friend’s father’s Ferrari. You’re curious about how fast this fancy sports car can accelerate. You decide to measure the acceleration by measuring the angle that the string makes with the vertical when the car is accelerating. Your friend’s father puts the pedal to the metal. Using a protractor, you measure that the angle the string makes with the vertical is 40 while the car is accelerating. What is the acceleration of the Ferrari? [Hints: Choose the decoration as the system for your force diagram. Use the vertical-component equation of Newton’s second law to find the magnitude of the force that the string exerts on the decoration. Then continue with the horizontal-component equation.]