Energy accounting in open, closed and isolated systems
Grade 11 Science Worksheet - Challenge Me
Circle the best answer, or write your answer on the line.
A motor does 500 J of work on a cart-and-ramp system. The cart gains 294 J of gravitational and 120 J of kinetic energy. How much thermal energy is made, Ari?
A motor does 300 J of work on a cart-and-ramp system. The cart gains 147 J of gravitational and 60 J of kinetic energy. How much thermal energy is made, Bo?
A motor does 800 J of work on a cart-and-ramp system. The cart gains 392 J of gravitational and 250 J of kinetic energy. How much thermal energy is made, Esme?
Why is a kettle with no lid an open system, Kira?
- Its water stays inside the kettle
- Steam, which is matter, leaves it
- No energy can cross its boundary
What change would make a lidless kettle a closed system, Luz?
- Thick insulation, with the top still open
- A tight lid, so no steam escapes
- A bigger heater
Noah says the total energy of an isolated system stays the same, even with friction inside it. Agree or disagree?
- Disagree: isolated systems leak heat
- Disagree: friction uses energy up
- Agree: friction moves energy between stores
Pia says a closed system's total energy can change. Agree or disagree?
- Agree: energy can cross its boundary
- Disagree: its matter stays the same, so its energy does too
- Disagree: closed means nothing crosses
A drone's battery gives out 900 J while it lifts a 2 kg box 30 m at a steady speed. With g = 9.8 m/s², how much goes to heat and moving air, Ren?
- 588 J
- 1488 J
- 312 J
A spring launcher stores 12 J. The ball it launches leaves with 9 J of kinetic energy. Where did the other 3 J go, Tala?
- Into the ball's mass
- Back into the spring
- Thermal energy and sound in the launcher
A 1 kg cart starts at rest, drops 2 m down a ramp and reaches 6 m/s. With g = 9.8 m/s², how much thermal energy did friction make, Zee?
- 1.6 J
- 18 J
- 37.6 J
- 19.6 J