University of Arkansas - AgriScience Project

AGRISCIENCE EXERCISE

PHYSICAL SCIENCES IN AGRICULTURE

Key Concept: Energy & Power Systems

Sub-Concept: Power Transmission

Agricultural Application: The agricultural industry relies on efficient transmission of power in mechanical systems.

Exercise: Calculating Horsepower Output of a Rechargeable Electric Screwdriver

Applied Principle(s): Work and Power in Mechanical Systems

Goals:

  1. Calculate horsepower when work output and time are known (or measured).
  2. Describe the relationship between torque, speed, and horsepower.


Materials:



References: Refer to any high school physics textbook

Procedures for Conducting the Activity:

1. Divide the class into pairs of students, and provide each with a data sheet and the necessary materials for this exercise.

2. Instruct the students to complete the activity as directed on their data sheets. You may wish to monitor their progress as they work; however, it is suggested that the students be left to follow the instructions and complete the activity on their own.

3. Once all groups have completed the exercise, discuss the answers to the discussion questions as a class. Be sure to make note of the practical agricultural applications of the principles demonstrated.



AGRISCIENCE EXERCISE

- Calculating the Horsepower Output of a Rechargeable Electric Screwdriver -

Student Data/Instruction Sheet

1. Gather the following materials:

2. Attach the largest diameter pulley to the shank of the screwdriver.

3. Secure one end of one string to the large diameter pulley; attach the other end of the string to the load (variable weight).

4. Hold the screwdriver at chest level. Have another student measure the distance from the top of the load to the bottom of the pulley. Record this measurement below:

Distance = __________

5. Use the spring scale to weigh the heaviest load the pulley and screwdriver combination will raise. Record the exact weight below.

Force = __________

6. Return the load to the floor. Raise the load by switching the screwdriver "on". Record the number of seconds required to raise the load. [how far?]

Time = __________

7. Calculate the horsepower developed by the screwdriver using the formula below:



Horsepower = Force (lbs) x Distance (ft)

Time (min) x 33,000

= x

x 33,000

= horsepower

8. Repeat steps 2 through 7, using the medium diameter pulley. Record your measurements and calculations below:

Distance = __________

Force = __________

Time = __________

Horsepower = __________

9. Repeat steps 2 through 7, using the smallest diameter pulley. Record your measurements and calculations below:

Distance = __________

Force = __________

Time = __________

Horsepower = __________

10. Return equipment and supplies to their proper locations.

11. Complete the following questions. Be prepared to discuss your answers with the class.

a. What is the definition of power?





Of horsepower?





b. Which pulley was able to raise the heaviest weight? __________ Explain why this is true.



















c. Briefly summarize the activity you just completed, and the observations you made.





































d. Briefly summarize what you have concluded as a result of your observation.

























Report any problems, comments or suggestions to the Webmaster.

This activity has been accessed content-type: text/html Could not get HTTP_REFERER Exitting times.