Thursday, Feb. 5th p. 160, 161

Thursday, Feb. 5th

1602/5/15 Thurs.L.T.: I can build a faster car with at least 2 redesigns with explanations of how they will increase the speed of the car. DO NOW: How could you increase the potential energy that goes into both the MT and fan cars? Explain.…………………………Reflection:Was I able to incorporate the 2 redesigns into my new car? How did they contribute to the speed of your car? Did the redesigns help your car the way you had expected? Are there other ideas you want to try? Why?

161Title: K’Nex Car Redesign

Official blueprints approved and taped in here or yesterday’s right side

…………….(tentative)Data:

Car T1 T2 T3 Avg. Time

Avg. Speed

5th period DO NOW

• Wesely: more PE if the car is tall• Carter: kinda disagree, if car is taller, it’ll have to be more spread out. The PE will spread out

more when it changes to KE• Donaven: disagree with Carter bc if more mass is higher, it’ll have more PE than rest of car• Anthony: agree with Carter bc more mass on wheels and won’t be able to move easily• Lauryn: not sure what you’re saying everyone. PE: E that is stored up and can be released.

More PE if you allow it to build up – once you release it, there’ll be more KE. Like the pressure on the MT I was talking about

• Anthony: agree with Lauryn. Modding your MT so there’s more pressure build up will make car go faster bc more PE

• Sonney: add more string to increase PE.• Chance: If you add more string, the MT swings its arm, after it’s done, the string will keep pulling

and the car will keep moving.• Lauryn: not if you have more E to make it move. String has nothing to do with it. (not

understanding). String allows to go certain distance but not source of car moving.• Guys: (disagree with L) You need longer string to keep axle from twirling back on itself and

braking (parking) the car• Anthony: agrees with both bc emphasis on modding car. More string if you mod car bc arm will

be pulled back more. More string is needed to keep puling with arm and not snapping.

4th period DO NOW

• Alex: more mass and using a slope will increase PE• Jayden: adding height and mass increases PE• Hope: increase in mass will decrease PE and create more KE• Jera: I agree with others. But what Hope said, if you increase the mass,

wouldn’t it decrease the PE?• Alex: I think you’re right bc on example, the bigger cat (more mass)

would create more KE than smaller cat.• Jera: So Hope is right.• Maurice: It also says (T and M) more mass = more PE. All PE transforms

into KE. • Alex: mass?• Jayson: snowball was going faster• Alex: Tractors (same mass) were going at dif speeds• Jera: greater KE = greater speed and mass. Maurice wrong? PE or KE?

3rd period DO NOW

• Add another battery for more PE• Take the back off MT and have MT arm pull back more• Wind up MT car more (tighter than before)• Fan car: add more powerful batteries• Batteries don’t determine the fan’s power… (some

conversation back and forth about this)• Add more propellers to fan car (?)• What could we do to reduce sliding friction? Smaller

wheels bc less mass to decrease friction • Point fan angled diagonally down• Take off some of the parts

2nd period DO NOW

• Taytum: less mass becomes more ability to create more PE• Jordan: nitro• Andrew: make car smaller but leave fan/MT the same. SO

more PE for less mass = greater impact• Luis: dif. Elevation, higher elevation• Sam: bigger wheels bc longer stride(?)• Luis: disagrees with Sam. Bigger wheels have more mass

which would slow it down. More friction.• Jordan: What Alex was saying.. Less string and less mass to

get less friction.• Alex: More string for more friction and less mass so gravity

doesn’t pull it down

Brainstorm of Redesigns and Rationales

Redesign Rationale

1. Using sharp edges2. Divide certain parts3. Elevate the start of the car 4. Adding another battery5. Once car is going, then add more mass (Does more KE necessarily mean more speed??)

1. Reduces air friction. Less friction = more motion.

2. reduce mass with reduce sliding friction. Less sliding friction means more motion.

3. More PE (adding gravitational PE to the fan battery/MT arm)

4. 2 batteries will have more PE than just 15. Increases KE (which we think will

increase speed?)

Jobs

• Everyone:• - rough draft blueprints in SNB • - inputs idea of how to redesign car

• Engineer A:• - master blueprints (main person who write and draws on main blueprints with

other Engineers’ input. Also makes executive decisions if there are arguments.)• Engineer B:• - master builder (person in charge of building with the help of other Engineers. Does

not mean that they are the only ones that touch materials!) Also gathers materials.

• Engineer C:• - master data collector (the leader who is responsible for collecting data.

Orchestrates who does what job and how to keep CVs controlled. Has official record of data in their SNB to share with others)

• Other jobs that may be needed: massing objects, getting approval from CEO, gathering tape, fixing fan, MT, sweeping, calculating speed, timing, etc.

Order of Events• 1. Blueprints: (Leader: Engineer A) - Wednesday

• - rough drafts in everyone’s SNBs• - official blueprints made and approved by CEO

• 2. Building: (Leader: Engineer B) – Thursday/Friday• - parts collected and built according to official blueprints

• 3. Data Collection: (Leader: Engineer C) – Thursday/Friday• - car taken to track and tested over 2 meter track for 3 trials• - calculations made to determine avg. speed.• - discussion and decisions made of how to improve speed even

more

• Blueprint Requirements:

• 1. A diagram of your new car design• 2.

• Make sure both Engineers have a rough draft in both SNBs before getting the official blueprints. Be specific!• Once the official blueprints are done, bring them to the CEO for

your StitchStamp of Approval. Then you may begin building.

Redesign Rationale

1. Use small wheels2. Use small wheels

1. Its lighter2. Less mass = less sliding friction. Less friction allows more motion.

Note: Make sure your rationale answers the question: How will this change help the car go faster?

Building Your Car• Engineer B is the leader but must follow blueprints• 1 MT or 1 fan• As many parts as are available (within reason – CEO

determines)• Altering stock cars can be used to save time, but must

be restored to their stock car build by the end of the period• Everything built must be broken down by the end of

each class period• Note: CEO may question engineers about redesigns and

HOW they will speed up your car!

2nd period car dataCar Type Avg. Time (sec) Avg. Speed (met/sec)

Fan 9.81 s +14.03 s + 11.73 s+ 3.43 s = 9.75 sec

d/t = 2met/9.75s = 0.21 met/s

Mousetrap 2.6 s + 1.76 s + 1.38 s = 1.91 sec

d/t = 2met/1.91s = 1.05 met/s

Original Q: Which will have an overall faster average speed: fan or MT?

3rd period car dataCar Type Avg. Time (sec) Avg. Speed (met/sec)

Fan 7.39 s + 4.28 s5.84 s

d/t = 2 met/5.84 s = 0.34 met/s

Mousetrap 1.87 + 1.95 s + 1.35 s1.72 s

d/t = 2 met/1.72 s = 1.16 met/s

4th period car dataCar Type Avg. Time (sec) Avg. Speed (met/sec)

Fan 4.30 s + 4.81 s + 4.60 s

4.57 s

d/t = 2 met/4.57 s = 0.44 met/s

Mousetrap 2.24 s + 5.48 s + 1.68 s + 1.74 s

2.79 s

d/t = 2 met/2.79 s = 0.72 met/s

Fan Car: 136.8 gramsMT Car: 210.0 grams

5th period car dataCar Type Avg. Time (sec) Avg. Speed (met/sec)

Fan 13.41 s + 7.88 s 10.65 s

d/t = 2 met/10.65s =0.19 met/s

Mousetrap 1.50 s + 1.64 s + 1.55 s

1.56 s

d/t = 2met/1.56s = 1.28 met/s

Fan Car: 136.8 gramsMT Car: 210.0 grams