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Why the Skate Park Rail Gets So Hot

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Why the Skate Park Rail Gets So Hot

Investigate how energy, type of matter and mass change temperature.

The heat lamp investigation

Read the passage and study the table. Then answer the questions.

Hot Rail, Cooler Ramp

On a sunny July day at Riverside Skate Park, Mateo Ruiz noticed that the steel grind rail felt much hotter than the wooden ramp beside it. His club coach checked with an infrared thermometer. At 9 a.m. the rail, the ramp and a full water bottle on the bench had all read about 22 °C. By 3 p.m., after hours in the same sunshine, the rail read 48 °C, the wooden ramp 36 °C and the water bottle 31 °C. Mateo wondered why objects in the same sunlight reach such different temperatures.

Back in science class, his group planned an investigation. Each sample had the same 10 cm by 10 cm top surface, painted the same flat black so that each one would absorb light in the same way. The samples were steel, concrete, wood and water held in a thin black tray. A thicker block or deeper tray has more mass. Every sample started at room temperature, 20 °C.

The teacher clamped a heat lamp 30 cm above each sample and switched it on and off. The group read a probe thermometer under the middle of each block, or in the stirred water, when the lamp went off. From the lamp's power and the size of the top surface, the teacher estimated that each sample took in about 160 J of energy for every minute under the lamp. The group repeated every trial on a second day, and each result came out within 1 °C of the first, so the table shows the first set of results.

Heat Lamp Trials (all samples start at 20 °C)
Trial	Material	Mass (g)	Lamp time (min)	Temp change (°C)
1	Steel	200	10	16
2	Concrete	200	10	9
3	Wood	200	10	5
4	Water	200	10	2
5	Steel	400	10	8
6	Steel	200	5	8

1.

About how much energy did each sample take in during a 10-minute trial? J

2.

What was the temperature of the concrete block at the end of Trial 2? °C

3.

Which trials show how the type of matter affects the temperature change?

A. Trials 1, 2, 3 and 4B. Trials 4, 5 and 6C. Trials 1 and 5D. Trials 1 and 6

4.

Compare Trials 1 and 5. Which statement do the data support?

A. Mass made no difference, because both blocks were made of steel.B. The 400 g block warmed more, since a bigger object holds more heat.C. Both took in the same energy, and the 400 g block warmed half as much.D. The 400 g block took in half as much energy, so it warmed less.

5.

Which 200 g sample would need the most energy to warm up by 10 °C?

A. ConcreteB. WoodC. SteelD. Water

6.

Use the pattern in the table to make a prediction.

If 100 g of water sat under the same lamp for 10 minutes, about how much would its temperature rise? °C

Back to the skate park

Use the table and the skate park observations.

7.

Sort each statement by whether the heat lamp data support it.

8.

Which is the best explanation for why the rail read 48 °C while the wooden ramp read 36 °C?

A. Steel warms more than wood from the same energy, so the rail likely got hotter.B. Wood gives off cold that keeps the ramp's temperature down.C. The ramp passed its thermal energy to the rail, making the rail hotter.D. The Sun sent energy to the rail in the morning and to the ramp later.

9.

After Trial 4, a classmate says the water took in almost no energy because its temperature rose by only 2 °C. What is the best reply?

A. You are right; a small temperature change means little energy went in.B. The water took in about the same energy as the steel but warms less per joule.C. The water gave energy back to the lamp while the lamp was switched on.D. The tray took in the lamp's energy, so none of it reached the water.

10.

The skate club wants new benches that stay as cool as possible in the afternoon sun. The choices are a steel bench or a concrete bench with the same mass and the same black finish. Which should they choose? Write a claim, give evidence from the table and explain your reasoning.