How fast, in meters per second, does an observer need to approach a stationary sound source in order to observe a 1.6 % increase in the emitted frequency?

The value is  

Explanation:

From the question we are told that

     The emitted frequency increased by

Let assume that the initial value of the emitted frequency is

Hence new frequency will be  

Generally from Doppler shift equation we have that

Here v  is the speed of sound with value  

          is the velocity of the sound source which is because it started from rest

           is the observer velocity So

Generally given that the observer id moving towards the source, the Doppler frequency becomes

=>                  

=>                

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.