Showing posts with label Forces. Show all posts
Showing posts with label Forces. Show all posts

Tuesday, August 23, 2011

Summer Science Camp: Hovercraft

The summer we offered a middle school version of science camp, we had fun making hovercrafts.  The "teacher-versions" were the full 4' (diameter) circles.  We had a handful of kids and they each made their own from a 2' (diameter) circle of plywood.

We followed Daryl Taylor's instructions, which I'll let you read on your own. 

In short:
The hovercraft is basically a large circle of plywood covered with plastic.  A shop vac motor (one whose motor can be switched to blow) is attached to the craft.  The motor pushes air into the space between the wood and the plastic, creating a buble.  The plastic has several small holes in it - the air is forced out of those holes and in turn the craft is pushed up, hovering above the ground.  Left alone, the hovercraft will stay in one place - add an outside force and you'll start to see physics laws in action!

Here are some pictures to aid in your construction (sorry, no action shots - go here to see Daryl's in action).

The bottom side:


In the center you'll place something to hold the plastic down.  Most people would use a plastic lid, we used something my friend's husband had lying around in his workshop - I'm not even sure what it is! 


You'll notice that ring of duct tape - it's not just decorative!  It reinforces the plastic, so you can cut holes in it without shredding the whole thing.


The top:
A masterpiece in duct tape:
It really does take vast amounts of duct tape to make sure the plastic is held down and no air will leak out. 

In the above picture, you'll notice a small hole cut out, near the bottom of the picture, slightly to the left.  That's where your shop-vac hose will connect to the hover craft, turning it from a heavy-piece-of-plywood-covered-with-duct-tape into a hovering-piece-of-plywood-covered-with-duct-tape!

It's not the most beautiful contraption ever, but it is a very cool demonstration of all kind of physics principles and it really does work!

Tuesday, June 14, 2011

Summer Science Camp: Slow Car Race

Students are each given a length of lumber (the size doesn't really matter, just make sure everyone has the same sized piece) and a matchbox car.  They need to create a ramp the car can travel down, but as slowly as possible. 

The students can position the wood in any way they wish and add anything to the wood to slow the car.  My only caveat is that they cannot ruin the wood - at the end of the "race" they need to be able to remove anything they've added and return it to me in the same condition in which they were given it (so it can be used again for another group). 

I spread out a variety of supplies:
  • a variety of types of paper
  • rubberbands
  • masking tape
  • glue
  • yarn
  • string
  • thread
  • toothpicks
  • popsicle sticks
  • straws

Students are welcome to ask for other supplies - if it's something I have in the lab, they're welcome to use it. 

The ramp construction must be completed within one session.  Even students who build quickly can remain busy by constantly testing and trying to improve upon their design.

Once construction is complete, all the ramps are set up.  The cars are placed at the top of the ramp and released at the same time.  The last car to reach the bottom is declared the winner.  Any cars that don't reach the bottom of the ramp (put a 5 or 10 minute time limit on the race) are disqualified from the competetion.

Tuesday, June 7, 2011

Summer Science Camp: Egg Drop

Egg drops are a classic science activity for a reason - they're fun!

The overall idea is this - you create some sort of packaging to protect a raw egg.  The protected egg is then carried to the top of a tall ladder or building and dropped to the ground.  The goal is to have the egg remain in tact. 

There are lots of variations....
...you can restrict the dimensions of the finished carrier.
...you can restrict the weight of the finished carrier.
...you can restrict the materials allowed in construction.
...or you can make it a free-for-all. 

A Google search will provide you with lots of ideas on how you might want to run your egg drop.  It will also provide you with grading guidelines and rubrics, if you're interested in using this activity during the school year. 

The younger the students, the fewer restrictions I'd place on the project. 

When we ran our science camp for elementary students, we had small boxes for each person/group to use as a starting point and then a whole variety of supplies, such as
  • yarn
  • fabric
  • packing peanuts
  • sponges
  • cotton balls
  • newspaper
  • balloons
  • straws
  • popsicle sticks
  • cotton batting
  • anything else we could think of
Because the students were you, we didn't put any restrictions on their construction - anything, inside or outside the box, was fair game. 

Students had one session to build.  For testing, a custodian carried the eggs in their carriers to one section of roof and dropped them for us.  We dropped them onto a black-top surface.  The kids were really excited to see how each would fare. 

Make sure you have a way to wash away any raw egg (i.e. a hose or bucket of water) that may get on to things.