6th grade extended response using RACES format
Use the information about potential and kinetic energy, forces and roller coasters and your knowledge of science to answer the questions.
Energy in a rollercoaster ride
Have you ever wondered why rollercoaster cars don't have engines? Vehicles don't always need that kind of power to make them go. But they do need energy of some sort. Before a rollercoaster ride begins, an electric winch winds the cars to the top of the first hill. That can take a while, because some rollercoasters start off nearly 100m (330ft) in the air!
The winch has to use energy to pull the rollercoasters up the hill, but that energy doesn't simply disappear. The rollercoaster cars store it just by being up in the air—and the higher up they are, the more energy they store. They'll use the same energy to race back down the hill when the ride begins. Because they have the ability (or potential) to use in the future energy that was stored in the past, we call the energy they're storing potential energy.
Once everyone's onboard, the cars are released and start to roll down. When they round the brow of the first hill, the force of gravity makes them hurtle downwards, so they accelerate (pick up more and more speed). As they accelerate, their potential energy turns into kinetic energy (the energy things have because they are moving). The further they go down the hill, the faster they go, and the more of their original potential energy is converted into kinetic energy.
At the start of the ride, the cars have a certain amount of potential energy.
They can never have any more energy than this, no matter how long the ride lasts.
Throughout the ride, they are constantly swapping back and forth between
potential and kinetic energy. Each time they race up a hill, they gain more
potential energy (by rising higher in the air), but they compensate for it by losing
some kinetic energy too (by slowing down). That's why rollercoaster cars always
go slower in the higher bits of a ride and faster in the lower bits.
In theory, this process could go on forever and the ride would never end.
But in practice, some of the potential energy the cars started off with is constantly
being used up by friction, when the wheels rub against the track. Air resistance
takes away more of the energy as well. Even the rattling noise the rollercoaster
makes uses up some of its energy. The cars lose more and more of their original
energy the longer the ride continues, and, since the cars have no engines, there's
no way of replacing it. That's why the loops on a rollercoaster ride always get
smaller and smaller. It's why rollercoaster rides must always come to an end
sooner or later. The cars simply run out of energy.
Extended-Response Item
Name: ______Date: ______Period: ______
Disney World has issued a challenge to roller coaster designers to determine who should build their next roller coaster. You'll need to prove that you can make a model of an exciting roller coaster that meets their criteria:
• Criterion 1: increase potential energy safely for the riders.
• Criterion 2: have the least effect on a rider’s maximum speed
As you respond to Part A and Part B, follow the directions below.
• Address all of the instructions in each prompt.
• Use evidence from the information provided and your own knowledge of science to support your responses.
Part A
Describe to Disney World how you plan to meet the criteria. In your description, answer four questions as they relate to each criterion:
1. How can potential energy be increased on a roller coaster?
______
2. How can kinetic energy be increased on a roller coaster?
______
3. How does the potential and kinetic energy change through the ride?
______
4. What forces are acting on the roller coaster?
______
Part B
"When designing a roller coaster, why do engineers have to understand potential & kinetic energy transformations and different forces acting on the riders?"
Using RACES format, the information above, criteria questions, and your knowledge of science, please write ONE paragraph answering the question fully.
Score Points
Part A (4 points maximum, 1 point for each question correctly answered)
Part B (5 point maximum, 1 point for each of the 5 parts of RACES)
Restate Answer Cite Explain Summarize