The tire on a mountain bike measures 30 in. in diameter. A rider picks up a thorn in her tire as she passes through a patch of goathead thorns. If she is traveling at a rate of 10 MPH, find the equation that would best model the height above ground (inches) that the thorn is at any time (seconds) from the time it first got on the tire. Make sure to think about which equation would best model the situation ie. y = sinx, y = cosx, y = -cosx