Uploaded August 2019 | Updated September 2026, 3 weeks ago
Can paper cut metal or coconut? It can if it rotates fast enough!
Equipment: angle grinder, paper, pencil, aluminum can, coconut, gloves, goggles, and a mask
Cut out several identical paper circles. Glue them together to make three-layer blades. Attach the circles to a saw. Put on gloves, protective eyewear, and a mask. Let's see if “paper can beat scissors!”
The incredible cutting properties of ordinary paper can be explained by the concept of “centrifugal force.” Centrifugal force is a fictitious force of inertia that arises from the rotation of the paper disks. This force is directed radially outward from the axis of rotation. In order to bend, the one needs to overcome the influence of centrifugal force. But how does this lead to paper cutting metal?
First, let’s talk about why sharp objects cut. It's all about the pressure. Blades are very thin, and therefore, the force applied to them creates strong pressure on the surface that needs to be cut. In other words, blades cut simply by pushing through the objects in their path. But pressure alone is not enough: this process also requires translational motion, as friction increases cutting efficiency. This is why we don’t just press downwards, but actively “saw” with a blade when making a cut.
As you know, friction causes objects to heat up – so why doesn’t the paper in our makeshift blade ignite from the friction? Firstly, the heat is distributed over the entire edge of the disk, and secondly, during its rotation, the paper manages to cool in the surrounding air.
Safety precautions: Danger! Only under adult supervision! Be sure to wear gloves, eyewear, and a face mask during the experiment!
Can paper cut metal or coconut? It can if it rotates fast enough!
Equipment: angle grinder, paper, pencil, aluminum can, coconut, gloves, goggles, and a mask
Cut out several identical paper circles. Glue them together to make three-layer blades. Attach the circles to a saw. Put on gloves, protective eyewear, and a mask. Let's see if “paper can beat scissors!”
The incredible cutting properties of ordinary paper can be explained by the concept of “centrifugal force.” Centrifugal force is a fictitious force of inertia that arises from the rotation of the paper disks. This force is directed radially outward from the axis of rotation. In order to bend, the one needs to overcome the influence of centrifugal force. But how does this lead to paper cutting metal?
First, let’s talk about why sharp objects cut. It's all about the pressure. Blades are very thin, and therefore, the force applied to them creates strong pressure on the surface that needs to be cut. In other words, blades cut simply by pushing through the objects in their path. But pressure alone is not enough: this process also requires translational motion, as friction increases cutting efficiency. This is why we don’t just press downwards, but actively “saw” with a blade when making a cut.
As you know, friction causes objects to heat up – so why doesn’t the paper in our makeshift blade ignite from the friction? Firstly, the heat is distributed over the entire edge of the disk, and secondly, during its rotation, the paper manages to cool in the surrounding air.
Safety precautions: Danger! Only under adult supervision! Be sure to wear gloves, eyewear, and a face mask during the experiment!
