Energy accounting in open, closed and isolated systems
Grade 11 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
A motor does 500 J of work on a cart-and-track system, while 320 J of heat leaves it into the room. By how much does the system's energy grow, Bo?
A motor does 1200 J of work on a cart-and-track system, while 750 J of heat leaves it into the room. By how much does the system's energy grow, Esme?
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Use this
Energy bar chart (example data), one bar per energy store, height in J. Before: kinetic 0 J; thermal 0 J. After: kinetic 150 J; thermal 50 J. A transfer arrow goes from the motor to the cart and track, labeled work 200 J. A dashed system boundary surrounds the cart and the track. The motor is outside it; its work arrow crosses the boundary inward.
In the energy bar chart, how much energy crosses the system boundary, Jun?
- 150 J
- 50 J
- 200 J
In the energy bar chart, how much of the motor's work ends up as thermal energy, Kira?
- 150 J
- 200 J, the whole amount
- 50 J
In the energy bar chart, why do the system's stores grow, Luz?
- Work from the motor crosses into the system
- Energy is made inside the system
- The track adds extra energy to the cart
A pot of soup simmers on a stove with no lid. Steam escapes and heat flows in. What kind of system is the soup, Milo?
- Closed: energy crosses but matter does not
- Open: matter and energy cross
- Isolated: nothing crosses
A sealed jar of water warms in the sun. What kind of system is the water in the jar, Noah?
- Open: matter and energy cross
- Closed: energy crosses but matter does not
- Isolated: nothing crosses
A box slides to a stop on a rough floor. Where did its kinetic energy go, Ren?
- Into thermal energy in the box and floor
- It was destroyed
- Into gravitational energy
A cart rolls to a stop on a carpet. What happened to the total energy of the cart, carpet and air, Tala?
- It was used up
- It grew, since the carpet warmed
- It stayed the same
A cart's brake pads squeal and warm as it slows. Which stores gain energy, Zee?
- Thermal energy and sound
- Kinetic energy
- Gravitational energy, since it slows