Lesson 3 Reading One Guide: Gravitational and Kinetic Energy
1. What happens when cans fall on modeling clay? You found that the higher the can is dropped, the more gravitational energy it has and the more it compacts the clay.
2. How does the roller coaster work? At the beginning of a ride, the coaster is usually pulled by a motor to the highest point of the ride. Its gravitational energy increases as it is pulled up. Once it reaches the top, it has all the energy it needs for the ride.
3. Does the roller coaster convert energy into different forms? Explain your answer. The rest of the ride is an experience in energy conversions. Conversions of gravitational energy into kinetic energy and back again
4. Describe how the pendulum’s movement near the bottom and the sides. Why does this happen? a pendulum moves faster near the bottom and slower at the sides. That happens because gravitational energy decreases as the pendulum goes down and is converted into kinetic energy. When the pendulum rises back up, its kinetic energy decreases because it is being transformed back to gravitational energy.
5. What does it mean when scientists say that the total amount of energy that the pendulum remains unchanged? That means when one type of energy increases, another type must decrease by the same amount.
6. Explain what energy conversions occur at the following points of the roller coaster work.
a. At Point A – The roller coaster has a lot of gravitational energy. The train’s large amount of gravitational energy is due to the fact that it is raised high above the ground. As the train rides down the first slope, such as at
b. Point B - it loses much of this gravitational energy and gains kinetic energy. The train speeds up as it loses height. Thus, its original gravitational energy is transformed into kinetic energy.
c. Point C - the train has maximum kinetic energy because all its gravitational energy is transformed into kinetic energy. The kinetic energy allows the train to go up the loop.
d. Point D - the train gains gravitational energy and loses kinetic energy (it slows down). As the ride continues, the train is continuously losing and gaining height, gaining and losing speed. Each gain in height corresponds to a decrease in speed as kinetic energy is converted into gravitational energy.