## How Fast Is that Rocket?

### Lisa LocklinSanta Rosa District Schools

#### Description

This lesson will allow the students to calculate the speed of a falling object using measurements from a falling rocket.

#### Objectives

The student knows that speed, velocity, and acceleration can be calculated, estimated, and defined.

The student knows that gravity is a universal force that every mass exerts on every other mass.

#### Materials

- Rocket Launching Kit ( 3 Rockets) (These rockets and engines can be purchased from a local variety store or through most science supply companies, Frey, Fisher Scientific, etc..)
- Rocket engines ( B,C,D, engines)
- Stop watches or timing device (one per group)
- Copies of the worksheet (one per student)
- Copies of the Data Sheet. (one per group or one per student - teacher's preference)
- Transparency of the Data Sheet. (for teacher's use) or you may choose to write the Data Sheet on the board.

#### Preparations

The teacher will need to:
1. Make copies of the worksheet, -Speed of a falling object- for each student. (To save paper, you may copy the two sheets of the attached file in 'duplex', i.e. front and back of the paper.)
2. Purchase 3 rockets and engines per class, (It is a good idea to have more than one engine per rocket.)
3. Aquire stopwatches - one for each group.
4. Discuss the activity with the administration as to location, time and date.
5. Secure an outside area to launch the rockets.
All materials will need to be collected before the activity begins.

#### Procedures

Day 1
1. Review with the students the concept of the acceleration of gravity and how is it a constant at 9.8 meters per second per second.
2. Explain to the students how to find the speed of a falling object.
3. Show several example problems on the board for the students to see the calculations involved.
4. Discuss how to find the acceleration of an object using the appropriate formula.
Final Velocity = 9.8m/sec/sec X time traveled
Acceleration = Final Velocity- Initial Velocity/Time
(** This, of course is a measure of AVERAGE ACCELERATION.)
5. Work example problems of each type with the students.
6. Distribute the worksheet, -Speed of a Falling Object-, to the students and allow them to work the remainder of the period on the worksheet. Assign the problems not completed for homework.

Day 2
1. Review the concept of gravitational acceleration and the speed of a falling object with the students.
2. Review the appropriate formulas with the students.
3. Take the students outside to launch the rockets.
(This activity works better with no wind blowing.)
The teacher will launch three rockets using three engine sizes. The parachutes need to be removed from the rockets.
3. Tell the students to time each rocket from the release of the top cap until each rocket reaches the ground. (In theory, the acceleration rate will be the same for each rocket launched although the rockets reach different heights.)
4. Tell the students the heights of each rocket are obtained from the data on the engine packet. 5. Tell the students to record the height of each rocket launched.
6. Escort the students back to the classroom and tell them to calculate the speeds, final velocities, and average accelerations of each rocket.
7. Compare the heights of the rockets with the final velocities of the rockets.
8. Let the students compare their answers with each other.
9. Have the students report data from their data sheet to the teacher to record on the board or on the overhead transparency.
10. Discuss the results with the class, then compare the data to the acceleration of gravity.
11. Discuss the average acceleration and how the same number 9.8m/sec/sec was calculated for each problem.
12. Have the students draw conclusions based on the information and record these conclusions on their data sheet.

#### Assessments

The students will be assessed by completion of the data sheets and evaluating the worksheets, points deemed appropriate by individual teachers.

#### Attached Files

The worksheet for day one and the data sheet for the lab activity.     File Extension: pdf