Editing Uphill Roller

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Physics]]:
| Center of Gravity
|-
| Grade Range:
| [[Elementary School]]
|-
| Format:
| [[Hands-on]]
|}

The uphill roller was first made by William Leybourn in the 17<sup>th</sup> century, and has been a curiosity item since it was first created. This demonstration will have students mesmerized, as well as some parents!

== Materials ==

* Uphill Roller

== Safety Precautions ==

Please read the General Safety Precautions section of the [[Demonstration Safety]] page before performing this demonstration.

== Demonstration ==

# Show students the ramp and roller, and ask them if they think it can roll up the ramp, and why they think it can or cannot. After getting answers, set the roller at the bottom of the ramp, and watch as it rolls uphill!
# Ask students for ideas on why it rolled uphill, and after taking ideas provide an explanation.

== Why This Works ==

The uphill roller works because of where the center of gravity is inside the double cone. An object's ''Center of Gravity'' is the point inside the object where the forces are balanced. This differs from an object's center of mass, which is where the mass of the object is centered, and can be outside of the object. By finding an object's center of gravity, one can then balance it on that point and it won't fall unless another force is applied!

The uphill roller consists of a set of diagonal bars connected to a block, and a double cone that rolls on them. The center of gravity for the double cone is inside the cone, aligned with the two endpoints on the cone. When the cone is set on the low end of the diagonal bars, the center of gravity is ''above'' the diagonal bars. Therefore, it will roll "up" the slope to get low enough that the center of gravity is between the bars!

== Additional Information ==

* This demonstration pairs well with the [[Magic Spoon]], the [[Inertia Trick]] and the [[Nailed It]] demonstrations.