5 Phase Change In Action

Becky McCoy

Title: PHASE CHANGE IN ACTION Timing: 50 Minutes

Target Audience: High school Physics

Objectives: Students Will Be Able To: • Use an investigation on melting icebergs to practice the use of heat equations. • Find applications of classroom knowledge in current events. The Teacher Will Be Able To: • Assess students’ progress in understanding heat.

Standards Assessed: Advanced Placement (AP) Physics B Competency Goal 31 • Objective 3.02: Evaluate and investigate temperature and heat

Misconception(s) Addressed: •

Misunderstanding of the temperature of a phase change.

Concept Map Vocabulary: •

All sections.

Becky McCoy

Lesson Plan Aim: Apply our classroom knowledge of heat to the environmental issue of melting icebergs. Physics Push-Up: Icebergs and Glaciers1 (5 min) Students should read the article “Meltdown” by Jenny Hogan. When finished, they should record their reaction in writing. Encourage students to make connections to the heat unit.

Teacher Talk: The Reality of Heat (5 min) Describe that icebergs and glaciers are both big blocks of ice, except icebergs float in water while glaciers glide along land. In light of the article “Meltdown”, ask students the following questions. • What are the effects of icebergs and glaciers melting at sea level? • Would the effect of a melting iceberg be any different than a melting glacier? • How might we discover the effects of icebergs on sea level, considering what we have discussed regarding heat?

Small Group Activity: Melting Icebergs2 (10 min) Students will perform an investigation in groups of four or five to discover the effect of melting icebergs on sea level. This activity is also an opportunity for students to practice using the equations discussed in class in a “real world” circumstance. Give students the following introduction to the activity: Scientists are worried about the effect of polar ice melting. The melting ice will cause ocean cooling and a decrease in the saltiness of the water. Also, melting ice will raise the sea level and could flood low-lying areas, including cities. However, scientists are less concerned about melting icebergs than about melting glaciers. Why is this the case? Materials: • Graduated cylinder • Water • Ice • Thermometers • Scale Balances Procedure: • Put 100mL of water in a graduated cylinder. Measure the mass of the graduated cylinder before and after the addition of the water to obtain the water’s mass. • Measure the temperature. • Put .1kg of ice in the water. Note what happens. • Observe the ice. What happens when it melts? • After five minutes, observe the level of the water. Has it changed?

Becky McCoy •

What does this experiment tell you about icebergs?

Whole Group Discussion: Observations and Data (10 min) Collect observations and data from each of the groups. Perform calculations to show what occurred mathematically in their investigation. Assume the ice had a temperature of 0oC. mass of water=mw mass of ice=mi=.1kg temperature of water=Tw temperature of ice=Ti=0oC specific heat of water/ice=c=1.0 heat of fusion=80 E=mcT E= (mw)(1.0)(Tw)+(.1kg)(1.0)(0oC) E-80=Total Energy (mw+.1kg)(1.0)(T)=Total Energy

Homework: Using the following equation, determine the temperature change of the water in your beaker. Imagine this change on a much larger scale. What might be a result? Heat=mc∆T=(mw+.1kg)(1.0) Find an article relating to and write one page about another current events topic relating to heat.

Exit Strategy: Post-Unit Assessment (7 min) Have students the same set of questions as the first lesson using the Heat and Temperature Quiz worksheet.

Assessment: •

Formative: o Written reactions as well as Question and Answer time regarding the “Meltdown” article. o Group discussion of laboratory results and observations. o Homework calculations and one page relation of heat to current events. o Post-Unit Assessment Quiz.

References: 1

- Hogan, J. “Meltdown”. New Scientist. London: Dec 25, 2004-Jan 1, 2005. Vol. 184, Issue. 2479/2480; pg. 25, 1 pgs 2 – Found online at: http://school.discoveryeducation.com/lessonplans

Becky McCoy

MELTDOWN

by Jenny Hogan

WHEN London is submerged and New York awash, we may look back on 2004 as the year when the water started rising. Observations collected from both North and South Poles show that the world's ice sheets and glaciers are disintegrating faster than anyone thought possible. In September we learned that the West Antarctic ice sheet is thinning following the collapse of the vast, floating Larsen B ice shelf in 2002. The Arctic Council warned in November that the continent could lose 60 per cent of its ice by 2100. Then, in December, came news that a giant glacier in Greenland, which was already the fastest flowing in the world, has doubled its speed in the past 10 years. And it's not just an ice shelf here, a glacier there. Measurements of ice fields around the world show they are shrinking more quickly than expected. Add up the losses from all the major ice fields and there is enough meltwater pouring into the oceans to increase sea level by almost one millimetre per year. That's three times more than the Intergovernmental Panel on Climate Change was bargaining on. What the panel didn't take account of were the subtle mechanisms amplifying the effects of gentle warming in the air and sea. When a glacier's surface ice melts, for example, water first creeps down through cracks and crevasses, weakening the ice, then pools beneath the glacier and lubricates its flow. Scientists had also underestimated how important floating tongues and shelves of ice are in stabilising the glaciers that fed them -as the collapse of the Larsen B shelf in Antarctica has shown. With the shelf gone, one glacier behind it thinned by 38 metres in just six months. Changes like these were expected to take centuries, but the weight of evidence now suggests that whole ice sheets could vanish in just a few decades. And, although no one is yet warning it will happen, if the entire Antarctic and Greenland ice sheets were to melt, sea levels would rise by up to 80 metres.

Hogan, J. “Meltdown”. New Scientist. London: Dec 25, 2004-Jan 1, 2005. Vol. 184, Issue. 2479/2480; pg. 25, 1 pgs

Becky McCoy Name ________________________________________________

Date __________

Heat & Temperature Quiz 1. Define Heat.

2. Define temperature.

3. Can water and ice co-exist at the same temperature without the ice melting or the water freezing? Provide an example.

4. Can water vapor and water co-exist at the same temperature without the water vapor condensing and the water boiling? Provide an example.

5. If 1kg of aluminum and a cup of1kg water at the same temperature are placed in a hot oven, after 5 minutes will the aluminum and water have the same temperature? Explain your reasoning.

6. On a cold winter morning, you get out of bed and walk across your bedroom rug to the tiled floor in the bathroom. Which floor surface has a higher temperature? Why?