Aroller coaster car rolls down a frictionless track, reaching speed v at the bottom. a. if you want the car to go twice as fast at the bottom, by what factor must you increase the height of the track? b. does your answer to part a depend on whether the track is straight or not? explain.

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?