Lab 9: Power

Name:

Date:

OBJECTIVE

To study and apply the equations power, and to learn the physical meaning of Watts and horsepower.

Stopwatch

Meter stick or measuring tape

Each person in your group will demonstrate power by walking or running up a flight of stairs.

Follow these steps to obtain the necessary data:

I. Before the runners begin, a measurement of the stairs must be made. Measure the height of a single step in meters and record the measurement in Data Table 1. Also, count the number of steps from the bottom to the top and record them in Data Table1. These two values will be used to compute the total distance traveled upward.

2. Record the mass of each runner in Data Table 2. (1 kg = 2.2 lbs)

3. One person responsible for timing will indicate when each person should Start. When the person begins running, the starter Starts timing and stops when the runner reaches the top of the stairs. Record this as in Data Table 2.

4. Repeat this measurement for each runner. When a time has been acquired for each runner, go through each runner once more and record these times as "Time#2" in Data Table2.

5. Compute the average time for each runner using Time #1 and #2 and record them in Data Table2.

Data

Data Table 1

Single Step Height (m)	Number of Steps	Total Height of Steps (m)
0.173 m	10

Data Table 2

Runner	Mass in kg	Time #1	Time #2	Avg. Time (s)
1	60 kg	35.3 s	34.2 s
2	65 kg	25.0 s	27.7 s
3	70 kg	24.1 s	28.3 s
4	55 kg	28.3 s	30.3 s
5	50 kg	34.3 s	30.3 s
6	80 kg	37.5 s	38.2 s

Calculations

For these calculations, we will need just a few formulas. These can be found from class notes and from your textbook. In the formula table below, fill in each formula as described. For the final formula, combine the first three. This result will be used for your lab calculations.

Description	Formula
Power in terms of work & time
Work in terms of force & distance (assume an angle of 0 degree)
Force in terms of mass & gravity
Power in terms of mass, gravity, distance & time

Using the last formula above and the average time of each runner, compute the power of each runner in Watts and record the value below. Then convert this number to horsepower and record the value as well.

Calculation Table

Runner	Power (Watts)	Power (Horsepower)
1
2
3
4
5
6

Questions

Answer the following post-lab questions.

1. Which runner was most powerful?

1. What factors played a part in making that runner most powerful?