exam 2 bioe Flashcards
Difference between statics and dynamics
statics assumes a=0, path trajectory was always resolved
Dynamics you will be given acceleration or path trajectory and solve for the rest
two types of dynamics problems
” direct” and “indirect”
Direct dynamics
-forces are given, direction is unknown
-draw FBD calculate net forces
Calculate acceleration
Indirect Dynamics
-trajectory is given, net forces unknown
-Calculate velocity and acceleration, force and moment may be a function of time, location, etc
two primary methods for handleing dynamics problems
Equation of motion or energy methods
Equation of motion
-v=dx/dt, F=ma
-traditional projectile motion
-solve for velocity solve for trajectory
-function of time
Angular motion
- solve from perspective of the person rather than the observer
-curvilinear motion produces and acceleration towards the center of curvature
Energy methods
-force as a fucntion of location
-describe the force applied to a work input and then relate it to change in kinetic energy
- better for variable forces with respect to time
- W=KE
conservative forces
work done in a moving particle between two points is independent of the taken path (gravity)
Non-conservative forces
work doen in a moving particle between two points is dependent on the path (friction)
energy conservation
total energy of the system does not change
momentum
-gives a value that summarizes the history of interaction of the object
-its preserved in a colliosn
(equal and opposite)
perfectly elastic collisions
-Momentum and energy is conserved
-elastic behavior is perfectly linear
coefficient of restitution
e–> describes the ratio of the relative velocities befroe and after impact
- helps us find the height of an object per bounce
e values
e<1 continues to move in the same direction
e=1 perfectly elastic collision
e=0 plastic colision
