Dignity of Labour

ACTIVITY 5. POWER OF A STUDENT (Teacher’s Notes) PROCESS SKILLS: Measure, Observe, Compare, Test, Explain OBJECTIVE: The objective of this activity is to motivate the concept of power, or rate at which energy is transformed, and to apply it to the rate at which students do work to increase their gravitational potential energy in climbing a flight of stairs. IDEA: Students are asked to measure their gain in gravitational potential energy as they climb a flight of stairs, then to calculate the rate at which this potential energy is gained. This is followed by asking students to calculate their body’s energy needs for a day, both to perform various physical activities (including the climbing of stairs) and to maintain internal body functions. LEVEL: Middle Level (7, 8, and 9) DURATION: approximately 40 minutes STUDENT BACKGROUND: Students must be able to measure time with a stopwatch, measure distance with a meter stick, and enter data into and calculate with a spreadsheet. ADVANCE PREPARATION: Gather meter sticks and stop watches, arrange for use of computers and convenient staircase. MANAGEMENT TIPS: Elicit student responses to the Reflective Question before proceeding on to the activity. In checking student plans to measure and calculate the work they do climbing the stairs, make sure that students measure the distance walked up the stairs vertically, not along the slant of the stairs. They can determine their mass in kilograms by dividing their weight in pounds by 2.2 and their weight in newtons by multiplying their mass (in kg) by the Earth’s gravitational field, approximately 10 N/kg. One way to administer the time measurements is to line up students on the landing at the foot of the staircase to be climbed. Have the last student time the first student, then have all other students timed by the student who has just climbed the stairs. (This allows all the timing by a single stopwatch, transferred among student timers at the top of the stairs.) SAFETY: Require