Answer:
a) 30.84m/s
b) 348.32Hz
c) 32.34m/s
d) 289.69Hz
Explanation:
a) If 1 mile=1609,34m, and 1 hour=3600 seconds, then 69mph=69*1609.34m/3600s=30.84m/s
b) Based on Doppler effect:
/*I will take as positive direction the vector 
*/
c) 
d) 
Your speed is one of the only factors that has an effect on both your thinking distance and braking distance. Put simply, the faster you are going, the greater the distance travelled before you apply the brakes (thinking distance) and the vehicle comes to a complete stop (braking distance).
Answer:
This is a chemical property. If iron does rust, this is a slow chemical change since rust is an iron oxide with different properties than iron metal.
