1. Roller coasters are among the most popular amusement park rides. They are exhilarating and
thrilling to the people who ride them. How a roller coaster works is quite simple.
1. Almost all roller coasters start by going up a hill. The coaster is pulled up the hill by a
moving chain. A motor provides the energy for the moving chain. The energy from the
motor is transferred to the coaster.
2. At the top of the hill, the coaster has stored energy, or potential energy. It has the most
potential energy on the first hill. As the coaster goes over the top of the hill, the chain is
released and the coaster falls freely on the tracks.
3. As the coaster moves rapidly down the first hill, its potential energy changes into energy of
motion, or kinetic energy. It has kinetic energy because it is moving. This kinetic energy
carries it to the top of the next hill.
4. The kinetic energy is converted back into potential energy when the coaster reaches the top of
the second hill. As it goes down the second hill, the potential energy is again changed into
kinetic energy. This happens over and over on each hill until the coaster reaches the station
and is stopped by the coaster’s operator.
Note: Each hill of a roller coaster must be smaller than the one before it for the coaster to have
enough energy to make it over all of the hills. The coaster loses some of its energy between hills
because of track friction and air resistance.
Predict what would happen if the third hill on a roller coaster ride were bigger than the first hill.
Explain your answer.
If the third hill on a roller coaster ride were bigger than the first hill the cart would not make it over the third
hill. The cart would end up stuck between the second and third hill. It would end up being stuck because
the first hill would not have enough potential energy stored to convert into enough kinetic energy in order
for the cart to get over the third hill. (for every reaction there is an equal and opposite reaction but because
there is friction between the wheels of the cart and the track your first reaction must have a bit more energy
because energy is being lost throughout the ride potential energy always needs to be greater than kinetic
energy on a roller coaster)
4. A student goes skateboarding a few times a week. The student notices that she can go faster while
skating on some level surfaces than on others. She hypothesizes that speed has something to do with the
surface she is skating on. The student wants to design an experiment to test this hypothesis.
A. Identify the independent (manipulated) variable in the experiment.
*The independent variable is the type of surface that the girl is skateboarding on.
B. Identify the dependent (responding) variable in the experiment.
*The dependent variable is the speed at which the skateboard travels.
C. Identify two factors that will need to be held constant in the experiment.
1. Use the same skateboard and rider on each surface.
2. Use the same force / starting speed for each trial.
Base your answers to the following questions on the diagram below, which shows Earth
at one point in its orbit around the Sun. The length of daylight experienced at different
latitudes on a given date is shown on the diagram.
Base your
answers to the
following
questions on
5. Describe how the length of daylight changes from the Equator to the North Pole on
the diagram
the date shown.
below. The
diagram
*As one moves from the equator to the North Pole, the length of daylight decreases.
shows the
relative
strengths of
6. What season is beginning in the Northern Hemisphere?
the
gravitational
*The Northern Hemisphere is experiencing winter. (Tilted away from sun.)
force for
planets of
different
masses. The size of each planet represents the planet's relative mass. The arrow length indicates the
relative amount of gravitational pull that each planet would exert on an astronaut in space.
7. What is the relationship between the mass of the planets and the relative strength of their
gravitational pull?
*Larger, more massive planets, have stronger gravitational pulls.
8. Which three planets shown have less gravitational pull than Earth?
*Mercury, Mars, and Pluto have less gravitational pull than the Earth.
Base your answers to the following questions on the information and diagrams below.
Saltwater plants of the same species were grown in soil in separate containers with 1 liter of water. All of
the plants were the same height at the beginning of the experiment. Different amounts of salt were
dissolved in each container as shown in the diagrams. All other conditions were held constant.
Measurements for the final height of each plant are provided.
9. What is the control in this experiment?
*The tank of water with zero grams of salt would be the control.
10. State one conclusion, based on the information provided, about the growth of this type of saltwater
plant in water containing 0 to 20 grams of salt per liter.
*Higher concentrations of salt cause the saltwater plant to grow taller. In other words, the more salt in the
water, the taller the plant will grow. (Given the parameters of this investigation, the previous statement is
true. Who knows, if you add more than 20 grams of salt, things could change. The plant could die.)