## Torque

**Torque****is the twisting effect caused by a force applied at a distance from point of rotation.**

**It provides a simple way for testing and measuring the rotational movement of an object.**

**Torque is used to find and measure the effect of a force that causes an object to rotate about an axis. The most common use of torque is found in the household tool, the torque wrench. This tool uses torque to tighten and loosen bolts and other objects. Torque can also be found in many everyday situations, including the opening and closing of a hinged door. It is frequently used in the fields of mechanical and automotive engineering, as well as in physics.**

__Pivot or fulcrum__is the fixed point about which an object rotates.

__Lever arm (r or d)__is the perpendicular distance from pivot to point of application of the force.

FORMULA:

FORMULA:

**Torque = F x d ( force x distance) or F x r ( force x lever arm)**

## Torque real life application → Seesaw

**Seesaws are a good example of torque in our daily life.**

**In the seesaw, the pivot ( centre point) is the bar that supports the seesaw. And the seesaw itself is a lever.**

When two children are roughly the same weight and they are each sitting on the ends of the seesaw at the equal distance from the center(pivot), the seesaw will be balanced ( net torque=0 ) because they're exerting equal and oppositely directed forces (gravitational force, or weight). Seesaw only works when it is balanced.

When two children are roughly the same weight and they are each sitting on the ends of the seesaw at the equal distance from the center(pivot), the seesaw will be balanced ( net torque=0 ) because they're exerting equal and oppositely directed forces (gravitational force, or weight). Seesaw only works when it is balanced.

## 单击此处进行编辑.

**However, sometimes children may encounter the situation that one kid is significantly heavier than the other sitting on one end of the seesaw in which causes the seesaw unbalanced.**

**In order to balance the seesaw, the heavier child will have to move closer to the center to achieve equilibrium.**

From the picture above, we can see that the girl is heavier than the boy because she has greater mass and weight. (M2 and W2)

Therefore, the girl has to move closer to the center in order to balance the seesaw ( net torque = 0 )

Let say we assume that the boy is 20kg and 2.1m away from the center of the seesaw.

How far does the girl need to be sit from the pivot to make the seesaw balanced if she is 35kg.

(20kg)(9.8m/s^2)(2.1m) = (35kg)(9.8m/s^2)( ? m)

? (distance) = 1.2m

Answer: The girl has to sit 1.2m apart from the center in order to balance the seesaw.

Therefore, the girl has to move closer to the center in order to balance the seesaw ( net torque = 0 )

Let say we assume that the boy is 20kg and 2.1m away from the center of the seesaw.

How far does the girl need to be sit from the pivot to make the seesaw balanced if she is 35kg.

(20kg)(9.8m/s^2)(2.1m) = (35kg)(9.8m/s^2)( ? m)

? (distance) = 1.2m

Answer: The girl has to sit 1.2m apart from the center in order to balance the seesaw.