Energy Compressed KE 0 0 5. A block of wood rests on a frictionless surface and is attached to a spring, as shown below. When the spring is neither elongated nor compressed, the center of the block of wood is used as the reference point for the elastic potential energy of the block-spring system. The spring is then compressed to the left and released. Describe changes in the mechanical energy, kinetic energy, and elastic potential energy of the system between the time the spring is released and when it reaches its maximum elongation. Draw energy bar graphs showing the potential energy and kinetic energy of the system when the spring is compressed to the left, when it passes the reference point, and when it is fully elongated. Reference Point Elongated EPE KE EPE KE EPE Energy Energy Reference point 4. A 50.0-kg girl jumps onto a stationary 2.4-kg skateboard at 4.1 m/s. Determine the fraction of the original kinetic energy that was transformed to other forms due to the inelastic nature of the collision. 5. A 50.0-kg skater and skateboard leaves the right side of the ramp shown below at a speed of 7.0 m/s. a. If the ramp is frictionless, what was his initial speed at the top of the left side of the ramp? 2.0 m 6.0 m 0.4 m b. If the ramp were 12.0 m wide, how would this change the initial speed at the top of the left side of the ramp? Applying Physics Knowledge Answer the following questions. Use complete sentences. 1. Describe the energy changes that take place when the spring of a toy car is wound up and then released. 2. Why must the first hill of a roller-coaster ride be the highest hill? 3. Distinguish between an elastic collision and an inelastic collision. 4. A ball is thrown upward. Describe changes in the ball-Earth's system's mechanical energy, kinetic energy, and gravitational potential energy between the time the ball is released and the time the ball reaches its maximum height.