Which of the following statements is an accurate description of vibrations?

a. the frequency of infrasonic vibrations is much too high to be heard by humans.
b. neither ultrasonic nor infrasonic vibrations can be heard by humans.
c. infrasonic vibrations are used in sonar equipment as well as to detect flaws in steel castings.
d. ultrasonic vibrations have a frequency lower than the range for normal hearing.

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?