1. A weight is suspended from a spring and is moving up and down in a simple harmonic motion. At start, the weight is pushed up 6 cm above the resting 171 position, and then released. After 14 seconds, the weight reaches again to its highest position. Find the equation of the motion, and locate the weight with respect to the resting position after 20 seconds since it was released. 2. Suppose the lowest point of a Ferris wheel is 1.5 meters off the ground, and its radius is 15 m. It makes one complete revolution every 30 seconds. Starting at the lowest point, find a cosine function that gives the height above the ground of a riding child in terms of the time t in seconds.
3. A wooden ball is tied on a string 30 cm long, and is oscillating like a pendulum. See figure below. It is initially pulled back at 90° angle with the vertical, and is released with a push so that the ball reaches its maximum height back and forth. If it reaches its maximum height again after 3 seconds, find its height 10 seconds after it was released.