Test 1 Flashcards
What is Biomechanics
The study of forces and their effects on living organisms
What is Mechanics
The study of force and motion
What is Force
A push or a pull that has the ability to accelerate an object. vector quantity, that is usually measured in Newtons
What is Mass
The amount of matter an object is made of. Scalar quantity
What 5 steps do you use to describe motion
- Name the Action
- Name the plane it occurs in
- Name the segment that moves
- Name the joint at which it moves
- Give the angles of movement
What are the degrees of the joints in anatomical position
all joints are 0 degrees except the ankle is at 90 degrees
How does flexion/extension affects the angles of your body in anatmical position
flexion increases joint angle, extension decreases
What is internal force and an example
a force within a body that doesn’t (alone) accelerate the whole body mass.
Movement about a joint, or heart muscle
What is an external force and an example
outside Force put on an object that has the ability to accelerate the whole body mass (golfball being hit by a driver)
What is non-contact force
force without contact (GRAVITY)
What is a contact force
force from two or more objects coming in contact with each other
What are the 2 kinds of contact force
Normal force and Friction force
What is normal force
Force that is applied perpendicular to the contact surfaces
What is friction force
Force that is parallel to the contact surfaces
What are the two kinds of friction force
Static friction and dynamic friction
What is static friction
the friction force when there is no movement between the contact surfaces
What is dynamic fricition
the friction force when the two contact surfaces are moving past each other.
What is the relationship between dynamic and static friciton
Static friction is greater than dynamic friction
What is the scale for the coefficient of friction
0-1, 0 being very slippery, 1 being completely sticky
What is static friction
It’s when the sum of all of the forces on the object = 0. Meaning there is no acceleration
What is kinematics
The study of motion without regards to force
What is linear motion
Motion in a straight line
What are the two kinds of linear motion
Rectalinear and curvalinear
What is rectalinear motion and an example
All points move IN STRAIGHT LINES, the same direction and distance in the same amount of time.
(moving walkway)
What is curvalinear motion and an example
all points the same direction and distance in the same amount of time, but they do NOT move in straight lines (jumping on a tramp, landing in the same position but on a different part of the tramp)
What is angular motion (example)
Rotation, movement that often involves a fixed axis (feet stay still but you tip over)
What is general motion (example)
a combination of linear and angular motion (walking, body moves linearly, but segments move with angular motion)
What are the 4 kinematic variables
- Position
- Displacement
- Velocity
- Acceleration
What is position
Your location relative to a certain point
What is displacement
(P2-P1) where you are relative to where you once were. (Change in position)
What is velocity
displacement divided by time.
What is acceleration
change in velocity divided by time.
What is speed
distance divided by time
what is distance
how far you have traveled
What is the temporal midpoint
1/2 way point in time
When do you use the temporal midpoint
When you are trying to find average speed during that time (More measurements = more accuracy)
What is average speed
total distance/ total time
What is instantaneous speed
how fast you are traveling at a certain moment in time
How do we find the instantaneous speed
use the temporal midpoint to find the average speed of a very short period of time.
Is the acceleration of a projectile constant
- horizontal
- vertical
Yes to both
- 0
- -9.81 m/s/s
is the velocity of a projectile constant
- for the x axis
- for the y axis
- Yes
2. No
What is the vertical velocity of a projectile at max height
0 m/s
what are the variables that affect dx
- angle
- horizontal velocity
- time it is in the air
- height of release
how does the angle affect dx
The higher the angle, the less horizontal velocity, but the greater the time in the air.
How does horizontal velocity affect dx
the faster it moves the more ground it can cover
How does time in the air affect dx
the longer it is in the air the more time is has to move horizontally
how does height of release affect dx
the higher you release it from the more time that it has in the air, but also the higher you move, the more you can lower the angle, and thereby increase horizontal velocity, without sacrificing too much time in the air
What is kinetics
the study of motion with regard to force
What is newtons 1st law
a body will have remain in motion unless acted upon by an outside force. (no acceleration)
What is inertia
an objects resistance to acceleration (quantified by mass)
What is momentum
Mass x Velocity
what does the u stand for in the momentum equations
velocity before impact
Why does post impact velocity matter
will in sports like baseball the speed of the ball after will be beneficial
what is an elastic collision
when momentum is mostly conserved (superballs)
What is an elastic collision
when momentum is mostly lost (playdough)
What is the coefficient of restitution
comparison of post impact velocities to pre impact velocites
what is the coefficient of restitution for elastic collisions , then inelastic collision
close to 1 for elastic, close to 0 for inelastic
What is Newtons 2nd law
(Law of acceleration) an outside force will cause a body to accelerate in the direction of the force, proportional to the magnitude of the force, inversly proportional to the mass of the body
What is impulse
force applied throughout a duration of time
how do you find impulse
- Average force X time
2. integral (space under curve) of the force x time graph
What does an impulse cause
Change in momentum (change in velocity)
What is newtons 3rd law
When a body puts a force on another body, that second body puts a reactionary force back on the first body that is equal in magnitude and opposite in direction.
What is Newtons law of gravitation
all bodies are attracted to one another proportional to the product of their masses over the square of the distance between them.
