Its direction is normal to the plane containing r and F. Torque is defined as the vector product of the force and the displacement to the axis: τ = F r Therefore, the magnitude of the torque is τ = Fr sinθ The measurement unit for torque is the newton-meter (Nm), which you should not confuse with the unit of work (1 newton-meter = 1 joule). Torque about some axis of rotation (also called moment of force) results from a force being exerted at a point not on the axis. Explain how a laboratory balance measures mass Theory Equilibrium A rigid body in static equilibrium must necessarily be in rotational equilibrium. Describe mechanical equilibrium of a rigid object 2. By measuring the forces and calculating the torques acting on this meter stick in different situations, you will experimentally verify the two equilibrium equations. The rigid object will be an ordinary wooden meter stick. In this experiment, you will examine torques, rotational equilibrium, and center of mass as they apply to a rigid object. By considering the translational motion of an object s center of mass (the motion of a point mass), and the rotational motion of University Physics, Exp 8: Torque, Equilibrium & Center of Gravity ģ the object about its center of mass, we can determine the complex motion of any extended object. The concept of center of mass is what allows us to study the motion and equilibrium of extended (real world) objects as if they were point objects. To be in static equilibrium, a rigid object must also be in rotational equilibrium. The vector sum of all the torques about an arbitrary axis must be zero. The vector sum of all the external forces acting on it must be zero. Two conditions must be met for a rigid object subject to a combination of external forces to be in mechanical equilibrium: 1. The designer needs to identify all the forces and torques that act on a structural element, and to ensure through design and materials selection that the element will safely tolerate the loads to be exerted on it.
Analyzing static equilibrium conditions is an essential part of architectural engineering. The static equilibrium condition is very important in civil engineering, applying to bridges, dams, buildings, statues, and balconies, and in our daily lives, applying to our ability to stand up, to drive around corners without overturning, and to slide a stein of beer the length of the bar without spilling it. In this experiment, you will investigate truly rigid bodies and static equilibrium. It is not a rigid body under these conditions. What has changed? Only the chair s shape. But if an elephant sits on the chair, it will most definitely be in equilibrium with all four legs resting solidly on the floor.
Is it in equilibrium as it sits on the floor? If, as often happens, one of its legs is a bit short, it will not be in equilibrium instead, it will wobble about the two diagonally-opposite longer legs. Equipment 1 Lab Balance 1 Meter stick 1 Balance Stand for meter stick 1 Set of Mass Hangers for meter stick 1 Hooked Mass Set 1 Small, Unknown Metal Mass Introduction Consider, for example, an ordinary chair. University Physics, Exp 8: Torque, Equilibrium & Center of Gravity Ģ Purpose In this experiment, you will investigate torques on rigid bodies and static equilibrium. 1 E X P E R I M E N T 8 Torque, Equilibrium & Center of Gravity Produced by the Physics Staff at Collin College Copyright Collin College Physics Department.
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