Year 9 Science · Unit 3 · Lesson 5
Challenge Worksheet
Learning Goals
1. List the eight forms of energy from the lesson. Circle the forms that are stored energy.
2. A student says: “A 1.2 kg dictionary resting on a shelf 1.5 m above the floor has no energy at all, because it is not moving.” Evaluate this claim. Include a GPE calculation using g = 9.8 m/s², and name two other forms of energy the dictionary has.
GPE J
3. Rooftop solar panels charge a home battery during the day. Trace the chain of energy changes from sunlight to the energy stored in the battery, naming the form at each stage. At night the battery gives back less energy than was put in: explain where the difference went.
Data: a trolley on a ramp
A class let a 2.0 kg trolley roll down a ramp from five different starting points. They filmed each run and used a video app, frame by frame, to find its speed at the bottom.
| Starting point | Speed at the bottom (m/s) | Kinetic energy (J) |
|---|---|---|
| A | 0.5 | 0.25 |
| B | 1.0 | |
| C | 1.5 | 2.25 |
| D | 2.0 | |
| E | 2.5 |
Source: sample class results.
4. Use KE = ½mv² to complete Table 1.
5. Draw a graph with speed on the horizontal axis and kinetic energy on the vertical axis. Join the points with a smooth curve.
6. A student claims: “Kinetic energy is proportional to speed. If you double the speed, you double the kinetic energy.” Use two pairs of values from Table 1 to test this claim. Then use your graph to estimate the speed that gives the trolley 3 J of kinetic energy.
Speed for 3 J m/s
Find the mistakes: a student’s answer
“Nuclear energy and chemical energy are basically the same thing, because both involve atoms. In both cases, atoms react with each other to release energy. The only real difference is that nuclear reactions happen at very high temperatures, like inside the Sun or a nuclear power station, whereas chemical reactions happen at lower temperatures, like gas burning in a stove. So nuclear energy is just a hotter version of chemical energy.”
7. Identify each error in the student’s answer, then rewrite it correctly. Your rewrite must say whether each type of energy is held in the bonds between atoms or in the nucleus, how each is released, and one piece of evidence that the two are different.