Energy, Machines, and Motion
Part Two: Machines
Lesson 11: The Inclined Plane
The activities in this lesson are designed to assess student’s abilities to perform good lab work and to demonstrate in writing their understanding of the scientific principals of energy, forces, work and power
Focus Question: What energy changes allow a falling body to light a bulb?
3. Lesson Set-up and Management
EALR 2: Inquiry
Core content: Questioning and Investigating
6-8 INQC Collecting, analyzing, and displaying data are essential aspects of all investigations.
EALR 3: Application
Core content: Science, Technology, and Solving Problems
6-8 AAPD The process of technological design begins by defining a problem, identifying criteria for a successful solution, followed by research to better understand the problem, and brainstorming potential solutions.
EALR 4: Physical Science
Core content: Balanced and Unbalanced Forces
6-8 PS1D Friction is a force that acts to slow or stop the motion of objects.
- Students learn how incline planes work.
- Students investigate how the force need to pull a load up an incline depends on the slope of the incline.
- Students compare the work of pulling a load up an incline with the work done in lifting the load straight up.
3. Lesson Set-Up and Management
Materials:
- Students will use the sled they constructed from Lesson 8 and will continue to use it through Lessons 11-16. Wheels will be added to reduce the force of friction in Lesson 11 and removed for Lessons 12-16.
- Students will need to use both spring scales. Have them use the 0-2 N spring scale for smaller forces for more accurate measurements.
- Show students how to attach the inline plane to the peg board.
Have a student hold the peg board while a different student inserts
the ramp into the peg board at a 90 degree angle. This will eliminate
damage to the nails on the incline plane and reduce the chances of the
peg board tipping backwards.
Have students use something that will bring the level of the ruler up to the height of the ramp. Placing a strip of tape at the 0.1 m or 10 cm mark. Students slide the ruler along the ramp until it is at the ten centimeter mark. Students should place a small piece of tape on this spot, then measure the distance from the beginning of the ramp to the marked location.
Student Management:
- Students are asked to calculate the slope of the ramp. This will be a new skill for them.
- Support students in developing a data table will make the inquiry run smoother.
- Lesson 11.2 students look at the relationship of effort distance
and effort force to calculate the work done to move a cart up a ramp.
The terms effort force, effort distance, load force and load distance
can be confusing to students, consider having students draw pictures
with labels to help understand the differences between these terms.
Illustration for load distance and load force.
Illustration for effort force and effort distance.
- Review the student sample graphs at the end of Lesson 11. Determine how much support your students will need to set up their data tables. You will need different levels of support depending on the grade level you teach this unit.
- Students will remove the wheels off of the cart for Lesson 12 and Lesson 13.
Writing Support:
- Inquiry 11.1students compare the force needed to pull the sled (no wheels) with the cart (sled with wheels). Students will be introduced to the word effort force after taking these two measurements. Students compare the differences in force and give a reason for the differences. Consider using a chart to collect this information (Guided Questions: Inquiry 11):
- Students write a procedure and develop a data table to test what
will happen to the force if the slope of the inclined plane is
increased. They are asked to write this information on Student Sheet
11.1. Consider having students generate this information in their
notebooks instead. (Student Sample)
- Consider having students chart claims and evidence from data
collected: Below is an example from a middle school student:
Claim
Evidence
The higher the slope on the ramp the higher the effort force
The effort force on the 8th hole when pulling up the cart was .63 Newtons which is lower than when it was pulled up on the 24th hole where the force was 2.16 Newtons. As you can see when the ramp is higher there is more effort force.
Reading Support:
- “Escape Route to Johnstown” gives the students an unusual application of an inclined plane after their investigations in Lesson 11.
Math Support:
- In Lesson 11.1 students are asked to calculate the slope in their investigation. Students may need support and guidance as they add this to their data tables.
- In Lesson 11.2 students will measure the effort distance. Review with students how to measure. Figure 11.5 in the student edition serves as a good example.
- Students may see slight difference is the work to pull the cart up the incline. Talk about these small differences in data and the net effect of the amount of work.