How to Find the Friction & Angle Measurements of a Figure With Rotational Symmetry

Rotational Symmetry Angle

• 1

  Mark with a pencil the center point or axis of a figure with rotational symmetry. Draw a straight line, with a pencil and straightedge, from the center point or axis to a specific point on the outside of the figure. For example, a gear would have a line drawn from the center axis to the pointed tip of a gear tooth.

• 2

  Draw lines, with a pencil and straightedge, from the center to similar points on the like elements in the figure with rotational symmetry. In the example, draw a line from the center to the tips of each of the teeth on the gear.

• 3

  Measure with a protractor centered on the center point or axis the angle between two adjacent radiating lines.

• 4

  Divide 360 degrees of a circle by the angle measurement between the two adjacent radiating lines. The resulting number is the order of the object with rotational symmetry.

Friction Measurement

• 5

  Measure the normal force on the figure with rotational symmetry. Ensure the force is accurate by finding the force normal to the axis of the figure with rotational symmetry when the object rotates about the axis.

• 6

  Measure the force of friction on a leg of the rotationally symmetric object when the object is static, find the normal force to the leg by calculating the vector angle of the force relative to the face of the leg and multiplying the cosine of the vector angle by the overall force applied to the leg of the object.

• 7

  Multiply the normal force by the friction coefficient to find the measurement of friction on a figure with rotational symmetry.