Free Body Diagrams

Free Body Diagrams

Stop Light

Fish Bowl and Logs in container

Mousetrap racecars

Friday, November 8, 2013

Mousetrap Racecar

The first part was challenge to complete was picking a good partner, and that was easy to do.

Quinn and I got the parts to build our car right away and started to brainstorm.

Criteria:

• Design, build and compete with a Mousetrap Racecar (at least 2 axles).
• Maintain a clean workspace

Constraints:

• One mousetrap
• No more than 12 inches of masking tape
• Fischertechnique robotics parts
• No more than 24 inches of string
• All materials must travel with your vehicle
• Work through the stages of the event
• Additional materials by Instructor approval

Achievement #1

"Brainiac"- brainstorm 10 ideas for your design

1. Dune buggy style- long axles with wheels far away from the body
2. Really fat tires
3. Wheels wide set in the back and close in the front
4. Wheels wide set in the front and close in the back
5. Use string to secure the axles to the mousetrap
6. Use tape to attach axle on bottom of the trap
7. Use a third set of wheel to propel the car
8. Use the plastic treads to keep the wheels straight
9. Connect all of the axles together like the wheels of a train
10. Set off the trap by pulling a piece of string

Achievement #2

"Visualize it!"- Create a sketch of design and label key parts

Achievement #3

"Build it!"- Build your design and document it with a photo

The evolution of our mousetrap racecar

Achievement #4

"The Price of Glory"- If each part you use costs $1, evaluate the total cost of your build

• 6 wheels: $6
• 8 yellow building pieces: $8
• 7 red attachment parts: $7
• 2 axles: $2
• 1 piece of string: $1
• 1 piece of tape: $1
• 1 mousetrap: $1

Total Cost: $26

Achievement #5

"Competitor"- compete in the 2nd Annual Mousetrap Racecar Challenge

Achievement #6

"Long Distance Winner!"- Travel the furthest in the distance race

Achievement #7

"Feedback"- Collect feedback

• + We won without adding extended length like

Achievement #8

"Re-work"- Change your build based on the experience with the race/feedback you collected. Document it

-Originally we had rubber bands on the 2 front wheels and the back 4 wheels

Race 1: (original build) We went 7 tiles and place 2nd to last

-We removed the rubber bands off the 2 outer rear wheels

Race 2: (Change 1) We only went 5 tiles

-We put the rubber bands back on the outer 2 rear wheels and removed the middle wheels and axle

Race 3: (Change 2) We went 10 tiles passing our furthest distance

-The string would unwind completely and then would rewind on the axle causing the car to go backwards.       We extended the length of the string a few inches

Race 4: (Change 3) We went 20 tiles and moved into 1st place

-The extra length of the string helped a lot, so we decided to make it a little longer

Race 5: (Change 4) The extra string ended up just getting tangled around the axle and gave us a worse result

Achievement #9

"Game Changer"- Develop a new rule or change to the game that you feel would make the event even better. Explain.

Creative Mode Challenge: Following the acceleration and distance events should be the creative mode challenge

• Each team during a set amount of time (10 minutes or so) can make a really creative change to their cars.
• With almost no limitations on what they want to add to it (no motors/battery powered additions)
• After the new addition have another distance race to see whose car can go the farthest

Achievement #10

"Name it"- Invent a name for an achievement that you think is better than one we currently have.

Change "Brainiac" to "Lightbulb Master": originating from Gru in Despicable Me whenever he comes up with a new idea

Achievement #11

"Leave it Cleaner Than You Found it!"- Did you leave your work space cleaner than you found it? Explain.

We left our work space cleaner than we found it by putting aside working on creating a blog post during class time to help sweep the floor and put away all the pieces of robotics kits covering the tables.

Achievement #12

"Design/Build"- What is a "Design/Build" process? How did your experience with this challenge relate to that? Why might you experience this in a career related to technical innovation?

The process is: define goals/needs of your build, brainstorm, prototype 1: labeled sketch/drawing, collaborate ideas for change, prototype 2: build the sketch, test it, feedback, change, and test again (keep changing and testing until satisfied). For this challenge we built our initial design and tried to just add things to that original idea, until the last minute when we couldn't get it to work. We decided to start from scratch and finally we got our car to move. During the races we changed our build a little bit each time until we were satisfied. When it comes to technical innovation, you won't know how to change things until you test them to see the flaws. You can't test them unless you design and build  them, so if you want to be successful in the field than you will definitely run into some design/build processes.

Centroids

CENTROIDS

Sheet 2

Sheet 1

Lever System

Sunday, November 3, 2013

Creating Our Own Pulley System

Our task was to work in a group and create a pulley system with a fixed and movable pulley.

We used a spring scale to measure the amount of force it took to lift the movable pulley and the weight we attached to it. It took .95 Newtons of force to lift it. Then using the pulley system we used the spring scale again to measure the amount of force needed to lift the movable pulley and weight. It took only .4 Newtons to lift the weight. The mechanical advantage is 2:1.

Activity 1.1.2 Simple Machines Practice Problems

We got to take a look at a few different real life problems using simple machines.

Simple Machines: Lever

EX 1:
       A first class lever, in static equilibrium, has a 50 lb resistance forces and 15 lb effort force. The lever's effort force is located 4 ft from the fulcrum.

1. Sketch and annotate lever system described above

2. Calculate:

Actual Mechanical Advantage (AMA)
AMA= Force Resistance/Force Effort
AMA= 50 lbs/15 lbs
AMA= 3.33

3. Static Equilibrium Calculations:

 DR= Distance of Resistance Force
 M= moment (Force x distance)
 Moment Effort + Moment Resistance
-->

∑

-->M_Fulcrum= 0

(15 lbs)(4 ft) + (50 lbs)(DR)= 0

50 lbs(DR) = 60 lbs/ft

DR= 1.2 ft

EX 2:
       A wheel barrow is used to lift a 200 lb load. The length from the wheel axle to the center of the load is 2 ft. The length from the wheel and axle to the effort is 5 ft.

1. Illustrate and annotate lever system described above

2. Calculate: 

Ideal Mechanical Advantage (IMA)
IMA= Distance(effort force)/Distance(resistant force)
IMA= 5 feet/ 2 feet
IMA= 2.5
3. Static Equilibrium Calculations: 

FE= Force of Effort Force 
M= moment (Force x distance)
 Moment Effort + Moment Resistance

∑ M_Fulcrum= 0

(200lbs)(2ft) + (5ft)(FE)= 0

5ft (FE) = 400 lbs/ft

FE= 80 lbs

EX 3:

       A medical technician uses a pair of 4 inch long tweezers to remove a wood sliver from a patient. The technician is applying 1 lb of squeezing force to the tweezers. If more than 1/5 lb of force is applied to the sliver, it will break and become difficult to remove.

1. Sketch and annotate lever system described above

2.  Calculate:

Actual Mechanical Advantage (AMA)
AMA= Force Resistance/Force Effort
AMA= 1 lb/ (1/5) lb
AMA= 0.2

3. Static Equilibrium Calculations:

DR= Distance of Effort Force
 M= moment (Force x distance)
 Moment Effort + Moment Resistance

∑ M_Fulcrum= 0

(4 in)(1/5 lb) + (1 lb)(DE)= 0

1 lb(DE) = (4/5) lb/in

DE= 0.8 in

Simple Machines: Pulley 

EX 1:

       A construction crew lifts approximately 560 lb of material several times during a day from a flatbed truck to a 32 ft rooftop. A block and tackle system with 50 lb of effort force is designed to lift the materials.

1. Calculate: 

Actual Mechanical Advantage (AMA)
AMA= Force Resistance/Force Effort
AMA= 560 lb/50 lb
AMA= 11.2

2. How many supporting strands will be needed in the pulley system?

2 x(# of moveable pulleys) + 1(if changing direction)= # of strands

(2 x 4) +1= 9 strands