##
* *Reflection: Real World Applications
Rocket Planes and Acceleration - Section 3: Student Activity

This lesson was created in order to have my students apply the acceleration formula in a real world scenario. It allows them to work with an object that actually exists and calculate the object's rate of acceleration. Most kids think that acceleration is a static value, like velocity, and describes an object's current condition. Rather, acceleration is a dynamic value that describes the change in an object's velocity.

It is important for the kids to see the space plane's initial velocity at lift-off and see the space plane's final velocity at around 50,000 m in altitude. Seeing those two very different numbers can hopefully instill in the students that acceleration is how velocity changes from initial to final velocity. Without examples that clearly show a discrepancy in changes of velocity, students will probably from a misconception that acceleration describes the current state of an object's velocity.

*Applying the acceleration formula to real applications*

*Real World Applications: Applying the acceleration formula to real applications*

# Rocket Planes and Acceleration

Lesson 6 of 6

## Objective: Students will be able to use the acceleration formula with a simulation of a rocket plane to calculate acceleration.

*85 minutes*

**MS-PS2 Motion and Stability: Forces and Interactions**

**PE**: MS-PS2-2 - Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.

**DCI**: PS2.A: Forces and Motion: All positions of objects and the directions of forces and motions must be described in an arbitrary choose reference frame and arbitrary chosen units of size. In order to share information with other people, these choices must also be shared.

**Science and Engineering Practices **3: Planning and Carrying Out Investigations - Collect data about the performance of a proposed object, tool, process or system under a range of conditions.

**Crosscutting Concept****: **Systems and System Models - Create a small-scale artificial system isolating variables (initial speed, final speed, and time) to calculate real-world measurements, such as acceleration.

This lesson was inspired when a representative from XCOR Aerospace came and spoke to the kids about the importance of commercial space travel and how engineers built their current rocket place named 'Lynx'. Many of my students asked how fast their rocket place went and I realized that if the kids had access to relevant data, they could calculate Lynx's rate of acceleration,

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#### Set-up

*15 min*

XCOR Aerospace's rocket plane is designed to hold two passengers and several payload experiments. It is able to take-off like a plane and ascend vertically for five minutes, reaching near-space. After it's engines shut down the 'Lynx' rocket place circles for about 25 minutes and lands on the original runway.

The students are to record vital information, such as initial speed, final speed, and time to reach final speed, to calculate the rocket plane's rate of acceleration.

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#### Student Activity

*25 min*

XCOR Aerospace Promotional Video is worth showing to the kids engage them and to give them a sense of what an XCOR's rocket plane is capable of.

The following video was made using Kerbal Space Program (KSP). The rocket plane shown in the video was modeled, as closely as possible, after the XCOR Aerospace 'Lynx' Rocket Plane. It was designed and tested by my son (Kerbal Space Program expert teenager!). Some changes were made in the design to mimic, as much as possible, the Lynx Rocket Plane. My son was impressed with XCOR's flight plan, as he had difficulty matching the engineer's specifications. Perhaps in the future I could give this assignment (assuming we purchased a site license for KSP) to my class as an engineering project.

If you would like a physical copy of this video for your computer it is called: Rocket Plane - Acceleration and can be downloaded here or it can be found on Youtube. My file (in this section's resources) may give you more resolution to see the rocket plane's speed on the instrument panel.

The acceleration formula is used to determine the rocket planes rate of acceleration.

Your students will need to gather three pieces of data.

- Initial speed 'Vi' (from moment of take-off)
- Final speed 'Vf' (when the rocket plane deploys its landing gear)
- Time 't' (students' timers)

I had my students record the rocket plane's initial speed at the point it first takes-off from the runway (135.5 m/s). The final speed is recorded about four and a half minutes later (265.56 seconds) when the rocket plane is about 50,000 m above the Earth. The rocket plane's speed can be seen directly about the gimbal (round ball like flight instrument) on the screen. In the simulation the rocket plane deploys its landing gear, during vertical flight, when final speed should be recorded (678.4 m/s). I have my students time the event from the moment of take-off to the point of the landing gear deployment (about 4.5 minutes). Make sure they record the time in seconds (i.e. - 4 minutes 28.56 seconds = 268.56 seconds). The rocket plane's rate of acceleration is about 2.02 m/s/s.

Student Work Sample

The students had to draw a picture of the event, include three colors (minimum), show all the relevant information, include the acceleration formula, and how they arrived at an answer.

#### Resources

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#### Extension

*45 min*

I developed a Powerpoint presentation that teaching kids how to use the acceleration formula.

Feel free to make modification if necessary.

#### Resources

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