gensci

motion

- a constant part of our daily experience
- understanding motion allows us to make critical decisions

translational motion

- the movement of an object from one location to another
- unlike rotational motion (spinning), in translational motion, every part of the object moves the same distance in the same direction

distance (d)

- the total length of the path traveled
- it doesn’t care about the directions
- if you walk 5m forward and 5m back, distance is 10m.

displacement (d→)

- the straight-line change in position from start to end
- if you return to the start, displacement is 0m

scalar quantity

has magnitude only (numbers)

vector quantity

has both magnitude and direction

speed (v)

- a scalar quantity that tells us how fast something is moving
- it ignores direction

velocity (v→)

- a vector quantity that tells us the rate at which an object changes position
- it includes how fast and which direction

positive

moving in the designated "forward" or East direction.

negative

moving in the opposite direction(West orBackward).

acceleration

- describes how velocity changes over time.
- includes speeding up, slowing down, or changing direction
- like velocity, acceleration is a vector
- it has both magnitude and direction
- we measure it in meters per secondsquared(m/s²)

positive acceleration

usually refers to an object speedingupinthepositive directio

deceleration

- refers to negative acceleration
- this happens when an object slowsdown(braking)

momentum (p→)

- a measure of an object's motion and its resistance to stopping
- it is directly proportional to mass and velocity
- because velocity is a vector, momentum is also a vector with both magnitude and direction
- the direction of motion is critical when calculating total momentum
- two objects with the same mass and speed have different momenta if their directions differ

Impulse-Momentum Theorem

for a fixed change in momentum, Force and Time are inversely related.

extending impact time

safety devices are designed to extend Impact Time to reduce Peak Force

crumple zones

deform to absorb energy and lengthen collision duration

airbags

cushion passengers, slowing them down gradually rather than instantly

seatbelts

stretch slightly to increase stopping time

Conservation of Momentum

in a closed and isolated system (no external forces), the total momentum remains constant.

before interaction

total momentum is calculated

interaction

objects collide or explode.

after interaction

objects collide or explode.

collisions

all collisions conserve momentum, but they differ in Kinetic Energy (KE)

elastic

- KE and momentum is conserved, clean bounce no heat generation
- objects involve hard, non-deforming surfaces
- bounce off, separate (ex: billiards, atoms)

inelastic

- KE is Lost but momentumis conserved
- energy transforms into heat, sound, deformation
- objects bounce but may be permanentlydentedor slowed

perfectly inelastic

- Max KE Loss. Objects stick together.
- ex: Dart in board, Train coupling

rotational motion

- occurs when an object spins or turnsaroundafixed axis
- unlike Translational Motion (movinginastraightline), rotational motion involves spinninginplace
- every point on the object follows acircularpatharound the center

axis of rotation

the central line around which the object turns

path

the route traced by any point on the object

radius

the straight-line distance from a specific point to the axis

degrees

- familiar unit
- a full circle is 360°

radians

- the standard unit for physics
- one radian is the angle formed whenthearclength (s) equals the radius (r)

translational motion

- movement in a straight line
- examples include running forward, gliding across the floor, or throwing an object

rotational motion

- rotational movement around a fixed point or axis
- examples include joints rotating like the shoulder, elbow, or knee

bones

function as rotating levers.

joints

function as the axes of rotation (Shoulders, Hips, Knees) natural body rotation

sports

optimizing technique for speed and powe

lever

- one of the oldest and most commonly used simple machines. It operates by rotating a rigid bar around a fixed point called the fulcrum, allowing a small effort to move a large load depending on its design
- a simple machine made of a rigid bar that pivots on a fixed point called the fulcrum

effort

the force applied

load

the object being moved

first-class lever

- the fulcrum is between the effort and the load(e.g.,scissors, seesaw)
- this type can multiply force or distance depending on the arm lengths

second-class lever

the load is between the fulcrum and the effort (e.g., wheelbarrow nutcracker), providing a mechanical advantage in lifting heavy loads

third-class lever

- the effort is applied between the fulcrum and theload(e.g., broom, baseball bat)
- these are commonly used to increasespeedandrange of motion rather than to reduce effort