Pk2: CH 1. Forced on Motion

Forces

push or pull: has he ability to accelerate an object

Units of measurement for Force

Lbs=pounds

Newton = 1kg=2.205 lb.225lbs

Weight = ma(g)

Scalar

mathematical representation of anything defined by magnitude(size)

ex: mass, distance, time, speed

Vector

Representations of anything defined by size and direction

What properties does a vector posses?

1. velocity, acceleration, force, and momentum

2. arrows

3. length of arrows/arrow heads can indicate magnitude and direction

4. can be added regardless of direction

5. can be broken down into horizontal and vertical components

What does sin,cosin, and tangent represent

Sin= opposite /hypotenuse

Cos= adjacent/ hypotenuse

Tan= opposite/ adjacent

Internal Forced

1. Tensile force: internal pulling force (tension)

2. Compressive force: internal pushing force (compression)

how does injury occur with internal forced?

tensile or compressive forces > internal forces structure = structure failure (muscle pull, fracture)

Muscles only produce…….

internal forces

External forces : an object interacts with their environment

What types are there?

1. Contact - object touches another

2. Non- contact force occurs between objects with contact ie: gravity, magnetic, electrical

Friction

integration between surfaces in contact ha move in opposite directions

2 types of friction

static friction: no movement (accceleration = 0)

dynamic: 2 surfaces move relative to another

What is NCF(normal contact force)

weight affecting the interactions between molecules of 2 surfaces ( if one increase so does the other equally)

Friction and surface area

SA= increase in mile. interaction

increase SA= decrease in pressure

net effect = no friction

True or false: Static friction is greater than dynamic friction

TRUE, static is Greater

True or false : harder a smoother surfaces generate less friction than softer and rougher ?

TRUE softer and rougher surfaces generate GREATER friction

Coefficient of friction

a mathematical number to account for different effects on friction different materials have

Locomotion

requirement friction forces

• traction = friction

• describes a force that initiated movement

Resultant Force

result of vector in addition of force

Colinear Forces

forces with the same line of action (can be adding or opposing)

Concurrent Forces

forces acting through the same point but not on the same line

What is pythagorean theorem

A*2+b*2=C*2

How do you combine vectors?

Head to Tail or Tail to tip method

Static Equilibrium

Forces acting on an object at rest ( not moving)

SumF=ma, a=0 in static sumF=0