irunphysics

Today the groups were running some trials to see how close to 20 feet we could get.  It was pretty busy in the classroom and unfortunately I didn't get any pictures or video.  I had two runs that were within an inch of 20 feet.  One run went past, then rolled back and stopped right near the line.  I was trying to find a way to be consistent with how much I pulled back the car.  The distance the car is pulled back is also the distance that the mass falls pulling the cart forward. The force from the pull over that distance results in work being done to the cart.  Work results in a change in kinetic energy, which ultimately is a change in speed.  After the car passes under the mass the string no longer pulls on the cart and I rely on friction in the wheels to slow the cart down and stop it.  My first idea was to use a force probe to determine how much force I was pulling the cart back, but realized that that really didn't help because the force...

Had a number of successes yesterday, biggest is that I developed a way to propel the car.  👊 The next two big hurdles to clear are how do I release the car from the string and then how do I alter the design so that the car will stop at 20 feet. Today's goal is to get the car released from the string.  After that I can work on manipulating variables so that I can control the stopping distance. My original plan was to design the hook in Fusion360 and then print.  But before doing that I decided to make a hook with cardboard etc. to look at the functionality of it first. When I started with the cardboard, I realized that I couldn't visualize how the hook would look so I took a step even further back and decided to build with paper first. Here are my supplies... And my first types of hooks...(paper, then cardboard) and my trial run... And the hook didn't release.  I made the bend at a random angle which may have been to low to release, s...

Yesterday was the first day of the car challenge.  I didn't work on a car. 😞 So here is my first log...😀 I am thinking of using the gravitational potential energy of a raised mass to power my car.  The mass will be tied to the cart so that as the mass falls the cart will go.  It'll look something like this.... There are some things that I am concerned with right away.  😏 -How will I get the top pulley supported? -First how can I get the string to detatch from the car? -Will the mass smash the car? -Will the car run into the lower pulley? -How will I get the car to stop at 20 feet?  Can this be accomplished by varying the mass or should I put a lock on the cart so the wheels lock up after traveling the distance. I collected some parts and think I have a good start.  The posts should be able to support the hanging mass.  I'll have to start throwing it together and find out what other problems I run into (I know there will be some...