Amy counts the wave crests traveling down a stretched string. five wave crests pass amy in two seconds. what is the frequency of the wave?
a. 5.0 hz
b. 2.5 hz
c. 10 hz
d. 2.0 hz

The frequency is 5 wave crests / 2 seconds= 5 crests / 2s=2.5c/s
 so it is B. 2.5 Hz 

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.

The answer is -6hope this