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Activity | How Fast Can You Work? Background Information: Work equals force times the distance through which the force acts. Force is expressed in Newtons (N) and distance is expressed in meters (m). Work is expressed in newton-meters, or the simplification, joules (J). The rate at which work is done is called power. Power equals work divided by time. If work is in Joules (J) and time is in seconds (s), power is expressed in joules/second, or the simplification watt (W). James Watt was a British scientist who invented the steam engine. To find out how the power of his engine compared to that of a horse, Watt measured how fast an average horse could do work. He found the answer and expressed the amount of work performed per second as horsepower. One horsepower is the equivalent of 746 W. Purpose: In this activity, we will experience the concepts of Work and Power using simple classroom materials. Please complete the following activity with a partner. You need to complete the data collection for both you AND your partner. If you are working in a group of 3, you must have YOUR data and one other person in your groups. Pre-Lab Questions: 1. What has to happen in order for a force to do work on an object? the object has to have force exerted and has to be in motion to do work. 2. What is the formula for work? work = power/time 3. What is the formula for power? Power = work/time 4. Do you do more work climbing the stairs quickly or climbing the stairs slowly? It would be the same amount of work as you apply the same amount of force and your weight stays the same, as well as the distance 1

Activity | How Fast Can You Work? 5. 5. Does it take more power to climb stairs quickly or climb stairs slowly? It takes more power to climb the stairs more quickly. Procedure: Calculate the work and power that you can do with different muscle groups. PART 1- ARMS 1. Measure the mass of the Bowling Ball Bowling Ball 11.3 kg (Remember to check the units on the scale you are using. 1 lb = 0.454 kg OR 2.2 lbs = 1 kg) 2. Using a meter stick, measure 2 meters from the floor and put a piece of tape on the wall. 3. Lift each bowling ball from the floor to the 2-meter mark. Record your data in the chart below: ARMS Mass (kg) Distance (m) Force (N) F= mg Time (s) Work (J) W = Fd Power (W) P= W/t You – Bowling ball #1 (Slow) 11.3 2 110.74 1.6 221.48 65.14 You – Bowling Ball (fast) 11.3 2 110.74 3.4 221.48 138.43 Partner – Bowling Ball (slow) 11.3 2 110.74 2.51 221.48 76.11 Partner – Bowling Ball (fast) 11.3 2 119.74 .93 221.48 238.15 2

Activity | How Fast Can You Work? PART 2 - LEGS 1. Determine the vertical distance in meters from the first floor to the second floor. To do this, measure the height of each step and count the number of steps between the first and second floor. 2. Measure how long it takes you to walk up the stairs at a slow pace. Record your mass (kilograms) and time (seconds) in the data table. 3. Determine the force used on the stairs by taking your mass (kg) times the acceleration due to gravity (9.81 m/s 2 ) 4. Repeat the procedure but this time move at a faster pace. 5. Calculate the work and power that was produced from this activity and record your data in the table. 6. Repeat the steps above for your lab partner. LEGS Mass (kg) Distance (m) Force (N) F= mg Time (s) Work (J) W = Fd Power (W) P= W/t You – Slow 54 4.44 529.2 16.1 2349.65 145.94 You – Fast 54 4.44 529.2 6.22 2349.65 377.76 Partner – Slow 66 4.44 646.8 18.1 2871.79 158.66 Partner – Fast 66 4.44 646.8 6.71 2871.79 427.99 PART 3 - CHEST 1. Choose a true pushup (on toes) or a simple one (on your knees). 2. Use the bathroom scale to determine the “force” that the arms must apply when doing a push-up. Record this value in the data table. 3. Measure the distance in meters that the top of your shoulder moves in one push-up (from straight arms to bent arms) = .35 m 3

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