Define a design problem and weigh trade-offs
Grade 11 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
A hallway lamp must run 6,000 h. Each 60 W bulb lasts 1,000 h and costs $1. Power costs 12¢ per kWh. What is the total cost of bulbs and power, Ari?
A gym lamp must run 30,000 h. Each 15 W bulb lasts 10,000 h and costs $3. Power costs 12¢ per kWh. What is the total cost of bulbs and power, Bo?
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Desk-lamp bulbs, each about 800 lumens (power and life follow DOE's comparisons; prices are example data) (example data). Columns: bulb, power (W), life (h), price ($), contains mercury?. A, incandescent, 60, 1000, 1, no; B, CFL, 15, 10000, 3, yes; C, LED, 10, 25000, 4, no; D, premium LED, 8, 25000, 7, no. Constraints: at most 20 W and at most $5.
Using the table, which bulbs meet both limits, at most 20 W and at most $5 each, Jun?
- C and D, the two that use least power
- A and B, the two cheapest bulbs
- B, C and D, since each lasts 10,000 h or more
- B and C only
Use this
Desk-lamp bulbs, each about 800 lumens (power and life follow DOE's comparisons; prices are example data) (example data). Columns: bulb, power (W), life (h), price ($), contains mercury?. A, incandescent, 60, 1000, 1, no; B, CFL, 15, 10000, 3, yes; C, LED, 10, 25000, 4, no; D, premium LED, 8, 25000, 7, no. Constraints: at most 20 W, at most $5, and no mercury.
The school adds a third limit: no mercury in classrooms. Which one bulb passes all three limits, Kira?
- C, the LED
- D, the premium LED, which uses the least power
- B, the CFL, which uses 15 W
- A, the incandescent, which costs the least
Use this
Desk-lamp bulbs, each about 800 lumens (power and life follow DOE's comparisons; prices are example data) (example data). Columns: bulb, power (W), life (h), price ($), contains mercury?. A, incandescent, 60, 1000, 1, no; B, CFL, 15, 10000, 3, yes; C, LED, 10, 25000, 4, no; D, premium LED, 8, 25000, 7, no. Constraints: at most 20 W and at most $5.
Bulb D costs $3 more than bulb C and lasts as long. What does the table say the extra $3 buys, Luz?
- 2 W less power, a small gain
- No mercury, which C contains
- Twice the life of C, so half the replacements
- Light of 800 lumens, which C does not give
A spec says: 'The lamp must cost at most $20 and use as little power as possible.' Which part is a criterion, Milo?
- Use as little power as possible
- Both parts are criteria, since both involve money
- Cost at most $20
- Neither part, since power cannot be measured
A spec lists 'at least 300 lux at the desk', 'light as even as possible' and 'under 15 W'. Which two are constraints, Noah?
- At least 300 lux, and light as even as possible
- Light as even as possible, and under 15 W
- Not one, since a spec lists goals and not limits
- At least 300 lux, and under 15 W
A lamp is split into light source, stand and cord. Ren tests each part alone and all three pass. What comes next?
- Retest the light source, since it is the hottest part
- Nothing more, since the three parts passed their own tests
- Test the assembled lamp, since the parts may affect each other
- Retest the cord, since it is the weakest part of the lamp
A hot bulb sits close to a plastic stand. The bulb and the stand each passed alone. What does that show, Tala?
- The bulb must be changed to a cooler type of bulb
- Neither test checked how the bulb's heat affects the stand
- The stand must be made of metal instead of plastic
- The lamp is safe, since both parts passed their own tests
Which split of the lamp problem gives parts that can be solved and tested separately, Zee?
- The first half of the lamp and the second half, split down the middle
- Cheap parts, good parts and safe parts, each tested in turn
- The bulb, the bulb's color and the bulb's price, as three parts
- Light source, stand and power supply, each with its own target