chapter 8 Flashcards
for a system to be at true equilibrium, what must be true about the forces and torque
the components of the forces must all be zero and the net torque must be zero
when choosing a pivot point for a system at equilibrium, where should we pick
we should pick a point on top of an unknown force
if the center of gravity is over the base of support, what will happen
the torque will bring the car back down
if the center of gravity is directly over the pivot, what is it called
it is the critical angle
if the center of gravity is outside of the base of support, what will happen to the car
the gravitational troque will cause the car to roll ver
if you have a wider base of support or a lower center of gravity, what is true of the stability
you will have better stability
what is a restoring force
it is a force that restores a system to an equilibrium position
if a system has a restoring force, what kind of property does it have
elastic
what is hooke’s law
hook’s law states that the spring force is proportional to the displacement at the end of string
if we press a spring ∆x, what is true about the magnitude of the spring force?
it is the same magnitude in the opposite directiin
if we stretch a spring far, what happens to the spring force?
it pulls back harder with an equal magnitude in the opposite direction
what is rigidity
when something is elastic but it only undergoes small changes in dimension under normal forces
what does it mean to be pliant
objects that can be stretched easily or show large deformations with small forces
if you have thicker things, what is true about the spring constant
it will be larger, it is harder to stretch
if you have something long, what is true about its spring constant
it will be smaller, it is easier to stretch longer things since there are more atomic bonds that can stretch
what is the ratio of stress
it is the ratio of the force to the cross sectional area
what is the ratio of strain
it is a ratio of the change in length divided by the length
what is the elastic limit
it is the end of the elastic region of an object
if an object is within the linear region of the elastic region, what is true
the object will return to its initial length when the force causing the stretch is removed (proportionality remains)
if an object is within the elastic region but beyond the linear region, what happens to the object when the force is removed
the force is not linear and not proportional to the displacement but the object will return to its original length when the force is removed
if an object is past the elastic region and is within the elastic limit what happens
the object becomes permanently deformed
what is tensile strength
it is the largest stress a material can sustain before breaking
if the spring constant is large, what is true of the spring?
it is harder to stretch, it is stiffer
if the spring constant is small, what is true of the spring
it is easier to stretch, it is more elastic
