Exhibit: Pickup Points
To try to pick up a cone, you place your fingers on either side of it. As you do this, your fingers press onto the cone, exerting a force. Regardless of the angle of the cone, the force acts at a 90o angle to it.
As you squeeze, you also exert friction forces. These occur where your fingers touch the cone. This force is exerted from where your fingers touch the cone towards the point at the top, acting upwards. The harder you squeeze, the more your fingers make contact with the cone, increasing the force.
As the angle of the cone gets larger, it becomes harder to grip. This is because your fingers tend to slip upwards towards the point of the cone and you apply less force. This means the frictional force will be lower and you will find it harder to lift the cone out of its hole. In addition to this, less of the frictional force is directed upwards. The critical angle for lifting the cone is around 90 degrees.