Physics

Physics

admin Tue, 2008-08-12 08:50

Hovercraft

Hovercraft

admin Tue, 2008-08-12 08:50

Can teams use a remote control to start and/or stop their hovercraft?

Can teams use a remote control to start and/or stop their hovercraft?

admin Mon, 2016-11-07 19:17

No, as any remote control system would violate either the dimension requirements or the prohibition on integrated circuits.

Can we connect two 9V batteries in parallel? Voltage across any points will not exceed 9V as they are connected in parallel. This just gives us higher current capacity to drive two motors.

Can we connect two 9V batteries in parallel? Voltage across any points will not exceed 9V as they are connected in parallel. This just gives us higher current capacity to drive two motors.

admin Mon, 2016-11-07 19:10

Yes, this would be allowed.

Description state "MAY construct". Can students use commercial kits or models or should they be built "from scratch".

Description state "MAY construct". Can students use commercial kits or models or should they be built "from scratch".

admin Mon, 2016-11-07 19:00

Commercial kits may be used, as long as the SO building policy is followed: https://www.soinc.org/building_tools_policy

Do commercially available switches, such as dimmer switches, count as integrated circuits?

Do commercially available switches, such as dimmer switches, count as integrated circuits?

admin Mon, 2016-11-07 19:56

It depends on the specific switch. Some switches are purely mechanical (i.e. utilize a potentiometer) and are allowed. Others are digital (i.e. utilize an integrated circuit) and are not allowed.

For the definition of a "cushion of air": does the air have to have a way out of the cushion on the bottom or sides, or can it be designed similar to an air mattress?

For the definition of a "cushion of air": does the air have to have a way out of the cushion on the bottom or sides, or can it be designed similar to an air mattress?

admin Mon, 2016-11-07 20:10

Yes because it is not hovering unless air is coming out. The air must have some way of escaping (i.e. it should need to be actively replenished for the device to work, not just be a sealed inflatable chamber).

How high must the hovercraft hover?

How high must the hovercraft hover?

admin Mon, 2016-11-07 20:07

There is no set distance it must hover. If an event supervisor, from a normal observation point without having to get up and close to the hovercraft, can visually see it move down when pushed, then yes it levitates.

In Section 2, paragraph 5, sub paragraph f, the rules mention a target time and then identify it for C only. In section 3, paragraph 6, subparagraph b, the scoring says the time score gives a calculation involving a target time. Please clarify.

In Section 2, paragraph 5, sub paragraph f, the rules mention a target time and then identify it for C only. In section 3, paragraph 6, subparagraph b, the scoring says the time score gives a calculation involving a target time. Please clarify.

admin Mon, 2016-11-07 19:04

5.f. doesn't identify the target time for C only. It only mentions that the target length will be announced for Div. C only (since Div. B already knows the target length). The target time concept applies to both B and C. The reference to Div C is for the variable length that must be announced.

Integrated circuits may not be allowed, but are individual transistors allowed?

Integrated circuits may not be allowed, but are individual transistors allowed?

ceann Tue, 2017-03-07 20:40
A single transistor does NOT meet the definition of an integrated circuit and is allowed. However, most event supervisors won’t have the knowledge / ability to verify that a given small black box is a single transistor vs. an integrated circuit (for example, some voltage regulators look EXACTLY like a transistor but clearly are an IC). Competitors will be at risk to having their device DQ’d if they bring something with lots of transistors that can’t be verified in a timely manner by an unskilled supervisor.

Is a breadboard with resistors and/or transformers considered and integrated circuit?

Is a breadboard with resistors and/or transformers considered and integrated circuit?

admin Mon, 2016-11-07 19:19

No. A breadboard with discrete resistors and/or basic transformers is not an integrated circuit. Note though that some types of resistors and transformers ARE integrated circuits and hence are not allowed.

Is an Arduino an integrated circuit?

Is an Arduino an integrated circuit?

admin Mon, 2016-11-07 19:29

Yes, an Arduino contains many integrated circuits and is not legal.

Is the maximum dimensions of the skirt 19.5 x 30 cm when the hovercraft is inflated or deflated? Can the skirt be larger than those dimensions when the motor is not running?

Is the maximum dimensions of the skirt 19.5 x 30 cm when the hovercraft is inflated or deflated? Can the skirt be larger than those dimensions when the motor is not running?

admin Mon, 2016-11-07 20:25

The maximum dimension of the skirt is the same as the device, 19.5 cm wide x 30 cm long, both inflated and deflated. Students may tuck the uninflated skirt under the device prior to inflation.

Is the total voltage for the hovercraft 9V, or is 9 volts the maximum rated for each circuit? For example, may I have a separate 9V battery for each motor if they are not linked?

Is the total voltage for the hovercraft 9V, or is 9 volts the maximum rated for each circuit? For example, may I have a separate 9V battery for each motor if they are not linked?

admin Mon, 2016-11-07 19:12

Yes, multiple batteries may be used as long as they are not connected in such a way that the voltage exceeds 9 V in any circuit. Separate 9 V circuits are allowed.

Is there an interval for the target time of the competition. Ex-- between 5.0-25.0s in intervals of 1 second

Is there an interval for the target time of the competition. Ex-- between 5.0-25.0s in intervals of 1 second

admin Mon, 2016-11-07 19:53

No

Please define what the propeller shielding is (1/4 in diameter?).

Please define what the propeller shielding is (1/4 in diameter?).

admin Mon, 2016-11-07 20:28

The propeller(s) must be enclosed in such a way that there are no holes bigger than 1/4" in diameter in the enclosure. A 1/4" dowel rod must not be able to penetrate the material.

Shouldn't the denominator be "target time" instead of "run time"? Currently, if target time was 10s and run time was 4s, the time score would be TS = (1-(abs(4s -10s)/4s))x25 = (1-(6s/4s))x25 = (-0.5)x25 = -12.5 a negative number!

Shouldn't the denominator be "target time" instead of "run time"? Currently, if target time was 10s and run time was 4s, the time score would be TS = (1-(abs(4s -10s)/4s))x25 = (1-(6s/4s))x25 = (-0.5)x25 = -12.5 a negative number!

ceann Tue, 2017-03-07 20:47
The scoring formula as written is intentional. Rule 6.b. explicitly says the smallest possible TS is 0. The official Excel event scoresheet available on sonic.org automatically does this. Even if you get a TS of 0 due to the formula going negative, you still have a successful run and get a non-negative MS (note that rule 6.a. isn’t explicitly tied to the TS). The purpose here is NOT to have the fastest vehicle, but rather to have the most adjustable vehicle that can try to meet a target time. The key is that instead of thinking about it in terms of absolute TIME differences, the rules committee thought about it in terms of SPEED differences. That is, say the target time is 25 seconds. With the proposed modified formula, a team doing a run in 12.5 seconds (twice the speed) gets a time score of 12.5 points. However a team doing a run in 50 seconds (half the speed) gets a time score of 0. There is no simple formula that can perfectly balance faster vs. slower speeds, so the rules committee explicitly decided to ENCOURAGE lower speeds (both from a safety standpoint and because it’s a harder engineering challenge), so the formula as printed in the rules provides less penalty if you err on the side of a lower speed (e.g. overshooting the target time)

The 1/4" or larger dowel. Can any material be used (i.e. wood, plastic, metal), and must it be solid or can it be an optically opaque tube meeting the specified dimensions and purpose of breaking a light beam?

The 1/4" or larger dowel. Can any material be used (i.e. wood, plastic, metal), and must it be solid or can it be an optically opaque tube meeting the specified dimensions and purpose of breaking a light beam?

admin Mon, 2016-11-14 21:25

The dowel can be any material, but by definition a dowel is a solid cylindrical rod, hence a straw is not allowed.

The clarification on this rule is not entirely clear. If I found a commercially-available product containing a brushless motor attached to a fan, must it be labeled as a "cooling fan" to be legal?

The clarification on this rule is not entirely clear. If I found a commercially-available product containing a brushless motor attached to a fan, must it be labeled as a "cooling fan" to be legal?

ceann Thu, 2016-12-15 21:12
No. As long as it is a fan typically used for cooling electronics or computers it does not need to be labeled as such.

The rules say that Brushless motors and integrated circuits are not permitted, does this just refer to integrated circuits to control motors or things like adjustable voltage regulators and arduinos.

The rules say that Brushless motors and integrated circuits are not permitted, does this just refer to integrated circuits to control motors or things like adjustable voltage regulators and arduinos.

admin Mon, 2016-11-07 19:55

Note there is an official rules clarification related to this, available at: https://www.soinc.org/official_rules_clarif The integrated circuit prohibition refers to all components (including voltage regulators / arduinos) other than those specified in the rules clarification.

What constitutes an integrated circuit?(ie. are resistors, capacitors, transistors allowed? Operational Amplifiers?)

What constitutes an integrated circuit?(ie. are resistors, capacitors, transistors allowed? Operational Amplifiers?)

admin Mon, 2016-11-07 19:27

An integrated circuit is a circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for the purposes of construction and commerce. Most resistors and capacitors are not integrated circuits. Nearly all transistors and op-amps are integrated circuits.

Optics

Optics

admin Thu, 2009-09-10 15:37

Wind Power - Div B

Wind Power - Div B

admin Tue, 2008-08-12 08:51