Temperature, particle motion, and how much the temperature changes

Answer Key - Grade 8 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   A heater gives sample B the same energy as sample A. Ari heats two samples of water with the same amount of energy. How many °C does sample B rise?

   4 °C
2. 2.

   A heater gives sample B the same energy as sample A. A heater gives two samples of olive oil the same energy. How many °C does sample B rise, Bo?

   12 °C
3. 3.

   A heater gives sample B the same energy as sample A. Two samples of milk get the same energy from a heater. How many °C does sample B rise, Esme?

   6 °C
4. 4.

   Assume no energy leaves the cup. Kira mixes a small amount of hot water with a large amount of cold water. Which final temperature is most reasonable?

   • Between 50 °C and 80 °C, nearer 80 °C, since the hot water has faster particles than the cold water has, so it wins
   • Above 80 °C, since the temperatures of the two samples add together in the mixture when they are poured
   • Exactly 50 °C, the average of the two starting temperatures, since both samples are made of the same water
   • Well below 50 °C, much nearer 20 °C than 80 °C, since the larger cold mass has more particles to share the energy
5. 5.

   Assume no energy leaves the cup. Luz claims the final temperature is always the average of the two starting temperatures. Does the table support that?

   • No: each final temperature should match the hot water's, since hot particles dominate a mixture
   • No: only trial 1 matched the average, and the final temperature moved toward the larger mass
   • Yes: each final temperature sits between the two starting temperatures, which makes it an average
   • Yes: trial 1 matched the average, so the other two trials must have had measurement errors

6. Read this first

   Three samples with the same energy (example data)

   sample	mass (g)	temperature rise (°C)
   A	100	20
   B	100	8
   C	100	12

7. 6.

   Milo gives three 100 g samples the same energy. Which material needs the most energy per degree of warming?

   • Sample C, since its rise is in the middle, so it needs a middle amount of energy per degree
   • The three need equal energy per degree, since the heater gave each sample equal energy
   • Sample A, since it rose the most, so it must have absorbed the most energy
   • Sample B, since the same energy raised its temperature by the smallest amount
8. 7.

   All three samples get the same energy. Which material needs the most energy per gram per degree, Pia?

   • A, since it has the most mass and so took in the most energy from the heater
   • A and B tie, since both rose 10 °C and the heater gave each of them equal energy
   • B, since it rose 10 °C with just 100 g, so it absorbed the most energy of the three
   • C, since it warmed the least and had just 100 g to share the energy
9. 8.

   Ren plans a fair test of whether sand or water warms faster under a lamp. Which plan is best?

   • Use 100 g of each material in matching dishes under one lamp, but read each thermometer once at the end of 10 minutes instead of every minute
   • Use 100 g of sand and 200 g of water in matching dishes under one lamp, so the water has enough mass to show a clear change on the thermometer
   • Use 100 g of each material in matching dishes, put both the same distance from one lamp, and read both thermometers every minute for 10 minutes
   • Use 100 g of each material in matching dishes, but set the sand closer to the lamp than the water since sand looks darker and slower to warm

10. Lamp test, one dish of each (example data)

    material	mass (g)	minutes under the lamp	temperature rise (°C)
    Sand	100	10	22
    Water	200	10	8

11. 9.

    Tala says sand has a smaller specific heat than water. What change would make this test fair?

    • Keep both dishes as they are and report the result as certain, since the same lamp was used for both
    • Test 100 g of water for 10 minutes, so that only the material differs between the two dishes
    • Test 200 g of sand for 15 minutes, so that the sand has as much to warm up as the water has
    • Test 100 g of water for 20 minutes, so that it reaches the same temperature as the sand did
12. 10.

    Each dish held 100 g and sat under one lamp for 10 minutes. Each material was tested three times with 100 g under one lamp for 10 minutes. Which conclusion do the data support, Zee?

    • Sand rose about twice as much as water in each trial, so sand needs less energy per degree
    • Water needs less energy per degree, since its rise was the smaller one in each of the three trials
    • Trial 1 settles it, since 22 °C against 11 °C is clear and the other two trials add nothing
    • The sand results vary from 22 °C to 25 °C, so no conclusion about the two materials is possible