When you hold an object in your hand, the of the object tends to cause a rotation of the forearm with the elbow joint acting as the . The force applied by your biceps tries to counteract this rotation.
When forces applied to an object tend to cause rotation of the object, we say the force is causing a . The size of a torque depends on the size of the , the direction of the force, and the distance from the point to where the force acts.
The caused by a depends on the distance that force acts from the point. To feel this effect for yourself, try this:
Open a door by pushing to the door near the handle, which is far from the pivot point at the hinges.
Now apply the same force perpendicular to the door, but right next to the hinges.
Does the door rotate open just as it did before, or did you have to push with greater force to make the door rotate?
The only time a torque wont cause an object to start or stop rotating is when its cancelled out (balanced) by other torques, as we saw for the torque due to biceps tension and torque due to ball weight in the forearm example. When the torques all cancel out the is zero and the object must be in . An object in rotational equilibrium might be rotating, but it won’t change it’s rotation speed or direction. If an object in rotational equilibrium is not rotating then it will not start rotating as long as it remains in rotational equilibrium.
When a body’s is above the area formed by the the can provide the necessary to remain in .
The critical is reached when the passes outside of the . Beyond the tipping point, causes rotation away from the support base, so there is no available to cause the needed to cancel out the torque caused by gravity. The normal force acting on the point can help support the object’s weight, but it can’t create a because it’s not applied at any distance away from the pivot.
Now with a the object can not be in . The object will rotate around the edge of the and tip over. We often refer to structures (and bodies) that are resistant to tipping over as having greater stability.
- OpenStax University Physics, University Physics Volume 1. OpenStax CNX. Jul 11, 2018 http://email@example.com. ↵
the force of gravity on on object, typically in reference to the force of gravity caused by Earth or another celestial body
the central point, pin, or shaft on which a mechanism turns or oscillates
the force that is provided by an object in response to being pulled tight by forces acting from opposite ends, typically in reference to a rope, cable or wire
the result of a force applied to an object in such a way that the object would change its rotational speed, except when the torque is balanced by other torques
any interaction that causes objects with mass to change speed and/or direction of motion, except when balanced by other forces. We experience forces as pushes and pulls.
at an angle of 90° to a given line, plane, or surface
remaining unbalanced torque on an object
a state of having not net torque and no change in rotational motion
a point at which the force of gravity on body or system (weight) may be considered to act. In uniform gravity it is the same as the center of mass.
region defined by lines connecting points of contact with the supporting surface
the outward force supplied by an object in response to being compressed from opposite directions, typically in reference to solid objects.
the point at which an object is displaced from a region of stable equilibrium
attraction between two objects due to their mass as described by Newton's Universal Law of Gravitation