Good Afternoon,
What bluetooth modules can I use with the arduino and how would I go about using it? I basically need it to connect to an app on your phone send it data.
Also what kind of sensor would I use to tell if someone is sitting on it like in a car?
Thanks in advance! XD
Why ? (would you want a sensor to detect someone sitting in a car. That sounds suspicious. What are you making that would require that ?
The most common and cheapest BT modules used are the HC-05 & HC-06 modules.
(usually around $5.00 USD or so)
As far as the sensor you want to use.. 'It depends'...
Is just a simple there or not there reading you want? are you trying to gauge the weight or pressure? (as the tile implies?)
If the former,... is much easier, but depends on how/where you plan on mounting it? A simple switch/button or lever switch.. or even two pieces of conductive wire or something would work..
WHOA OunceofTech!
calm down.
while I normally agree.. if someone doesnt like a post.. they should just skip it...
(and I couldnt really think of anything suspicious myself you could be wanting to do).. I really didnt think the post/comment was that bad. Not helpful.. but hardly 'snarky'..
Some people are respectful of how their advice will be used and do not want to accidentally contribute to any illegal activities or do anyone's 'homework' for them..etc (you understand)
If you search for bluetooth and Arduino.. your bound to get more results than you care to read. 
or HC-05/06...etc
they are just like serial devices... and dead simple to use (even for me) 
Hope this helps
Thanks for the reply,
All I need is a there or not there sensor basically.
Cars have seat sensors built in so they know to trigger the seat belt warning sign.
...R