Statics Flashcards
What are the two types of equilibrium?
Stable and Unstable
When is an object in static equilibrium?
If the forces acting on it are such that it remains stationary
What is stable equilibrium?
Object returns to equilibrium after small displacement
What is unstable equilibrium?
Object does not return to equilibrium after small
displacement
An object with a wide base and a pointed top will be stable if placed on its based but unstable if placed on its point, why is this?
The torque produced by the weight force will act to rotate the object either back to the middle (stable case) or further form upright (unstable case)
What do we use to make an object rotate?
We apply a force at a distance away from the point of rotation (pivot).
The strength of the turning effect of the torque depends on what?
Depends on the magnitude of the force (F) and the length of the lever arm (d). Thus we can define torque τ =Fd Units: N m
A force applied to an object fixed to a pivot point via a rigid rod will cause what?
Angular acceleration, angular velocity of the object increases over time
How can one measure a torque?
Simple measurement tools such as spanners (wrenches), display some calibrated deflection or elongation in units of Nm.
What are the two conditions for static equilibrium?
1) For an object to be at rest Newton II says that the sum of the forces must be zero. Also the sum of the components of the forces in each direction(x, y, z) must be zero.
Second condition: Sum of the clockwise torques (moments) must equal sum of anticlockwise torques.
What is the centre of mass? (center of gravity)
The unique point where the weighted relative position of the distributed mass sums to zero, or the point where if a force is applied it moves in the direction of the force without rotating. The center of mass is the mean position of the mass in an object.
What occurs when you throw a spinning object?
When you throw a spinning object the centre of mass follows a parabolic path.
Down, increases and does curve
For static stability of an object on a surface, where is the centre of mass?
the vertical line through the centre of mass should pass through the supporting base
What is statics?
The branch of mechanics concerned with bodies at rest and forces in equilibrium.
What is equilibrium in statics?
A state of balance due to the equal action of opposing forces in a structure.
