#9 - Tau - Torque Mystery Cache

In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically the lowercase Greek letter tau.

Torque equation

The torque (tendency of an object to rotate) depends on three different factors:

τ = r F sin(θ)

where:

• r — Lever arm — the distance between the pivot point and the point of force application;
• F — Force acting on the object;
• θ — Angle between the force vector and lever arm. Typically, it is equal to 90°; and
• τ — Torque, whose units are newton-meters (symbol: N⋅m).

Imagine that you try to open a door. The pivot point is simply where the hinges are located. The closer you are to the hinges, the larger the force you must use.

Estimate a classic door of 80 cm width on which you apply a force at the edge of 375 N. What is the torque in Nm that you apply to the door ?

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