With a permanent marker, indicate the starting point of the wheel (zero seconds). Add a piece of blue painter’s tape to the side of the track, along its whole length. You can also track the wheel’s position over time. What do you notice? What do you think would happen if you were to divide the track into quarters? Into eighths? What do you notice? How fast do you think it is moving? You can use this relationship to get an estimate:ĭoes the speed of the wheel seem to change as it moves down the track? How can you tell? One way to find out is to use your timer to measure the time it takes to travel the first half of the track and compare it to the time it takes to travel the second half of the track. To begin investigating, position the wheel at the top of the track and let it roll down. Adjust the height of the track or re-center the wheel as needed. The wheel should take between twenty and thirty seconds to travel the length of the track.
![rolling disk graph rolling disk graph](https://venturebeat.com/wp-content/uploads/2018/08/dex.png)
Make sure it’s centered and will roll on its own with minimal wobble and without being pushed. Release the wheel so it rolls down the track. When the track is correctly spaced, tighten the wing nuts to fix it in place. Place the wheel on the track and adjust the track’s width so that the zones where the dowel tips begin to narrow are directly on top of the pipe (see photo below). Place both ends of the track on a stack of books so that the starting line is higher than the finish line. Make sure they’re secure, but loose enough so the track can be adjusted. Insert the set screws through the outermost holes of the mending plate, and screw the wing nuts on top (see photo below). Place the pipes parallel to each other to form a track for the wheel. Repeat this process with the second length of conduit pipe and the two remaining blocks. Be careful not to tighten the set screws too tightly or you could strip the threads. Tighten the set screws until the pipes are held firmly in place (see photo below). Place one block on each end of a length of conduit pipe, ensuring that the pipe is placed near the top of the block. Repeat this procedure with the other three blocks (see photos below). Make sure that the screw does not enter the hole (the pipe will fit there). Place a set screw into the hole and use an Allen wrench to screw it into the top of the block. Drill all the way into the previously drilled large hole (see photo below). Using the 9/64-inch bit, drill a hole into the top edge of the block. Use the ruler and pencil to find the center, drawing two intersecting lines as in the previous step. Turn one block to work along the top edge, above the hole you just drilled. Then, using the spade bit, drill a 3/4-inch (2 cm) hole all the way through the block. Use the center punch to make a mark where the lines intersect. Make another line approximately 1 inch (2.5 cm) down from the top edge of the block (see photos below). Using the ruler and pencil, make a line marking the vertical center on the face of one 1 x 2 x 4-inch (2.5 x 5 x 10 cm) wood block. Slide the dowel through the hole in the disk, making certain that the lengths on each side of the disk are equal. Use a pencil sharpener to create a point on each end of the dowel (see photos below). Use a saw to cut the dowel to a length of 3 1/8 inches (8 cm). Then use a 3/8-inch bit (10 mm) to drill a hole through center (see photos below).
![rolling disk graph rolling disk graph](http://www.jiutech.com/uploadfile/image/20150706/20150706165425122512.jpg)
Use a center punch to start a hole in the center of the disk.
![rolling disk graph rolling disk graph](https://i.stack.imgur.com/yS3v8.gif)
Place the disk on a scrap piece of thick wood. Alternatively, you can use a device called a center finder to locate the center (see right photo below). The circle’s center is at the intersection of the two lines (see left photo below). Then turn the disk 90 degrees and make a second line. In Part I you’ll build the wheel in Part II you’ll assemble the track.įind the center of the wooden disk by using a ruler to measure the greatest distance across the circle (the diameter) and marking it with a pencil or box cutter. Stack of books or something to elevate the track (not shown) Two 5-foot (1.5 m) lengths of 1/2-inch (1 cm) rigid metal conduit pipe Note: The actual size of the set screws is not crucial, but it is important that the screws, the holes in the mending plates, and the wing nuts are all the same size. Two 3-inch (7.5 cm) mending plates with #8 holes Thick block of scrap wood (or other protective drilling surface not shown)Įlectric drill and drill bits: 3/8-inch (10 mm) 3/4-inch (19 mm) spade bit 9/64-inch (3.5 mm)įour blocks of wood 1 x 2 x 4 inches (2.5 x 5 x 10 cm)
![rolling disk graph rolling disk graph](https://cherry2000.weebly.com/uploads/3/8/7/7/38773679/2655968.jpg)
Wooden disk, 4-5 inches (10-13 cm) in diameter (available online or in arts-and-crafts stores)