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Physics 110 CH3-4 by
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# Physics 110 CH3-4

## Chapter 3

### Position

Origin, A reference point

We give distance from the origin and the direction

Vector, Distance, Direction

Graphically, The position vector can be drawn as an arrow starting at the origin and ending with the arrowhead on the object, When drawing more than one position vector, choose a scale so the length of the vector arrow is proportional to the actual distance between the object and the origin

### Displacement

Change of the position vector, The final position vector minus the initial position vector, Vector subtraction, To subract a vector is to add its opposite, (a vector with the sema magnitude but opposite direction)

Any direction in the horizontal plane can be specified by giving an angle with respect to the directions of the compass

### Velocity

Vector, Magnitude, Speed, Direction, Direction of motion

Velocity depends on both the displacement and the time interval

Average Velocity, Product of..., Vector, Displacement, A positive scalar, The inverse of the time interval, Slope of chord, rise / run, Chord- the slope of a line connecting two points

Instantaneous Velocity, A vector quantity whose magnitude is the speed and whose direction is the direction of motion, Can be used to calculate the displacement of the object during a very short time interval

Rate of change of position

### Newton's Second Law of Motion

The rate of change of the velocity is proportional to the net force and inversely proportional to the mass of the object

F = Ma, F is net force, M is mass, a is acceleration, The rate of change of the velocity is acceleration

When the net force is constant, the acceleration is also constant

SI UNITS, 1N= 1 kg*(m/s)/s, Acceleration, (m/s)/s, the rate of change of velocity, is inversely proportional to the object's mass, Force, Newton

Instantaneous acceleration, calculate the average acceleration during a very short time interval

Average acceleration

Problem solving strategy, Decide what objects will have Newton's 2nd law applied to them, identify all the external forces acting on that object, draw a free-body diagram to show all the forces acting on the object, Choose a coordinate system, Find the net force by adding the forces as vectors, relate the acceleration to the change in the velocity vector during a time interval of interest

### Mass

Measure of object's inertia, the amount of resistance of changes in velocity

## Chapter 4

### Kinematics

Study of linear motion, Break the complicated motion into intervals

Types of motion, Non-constant Acceleration, Constant Acceleration, a = 0 (m/s)/s, Equilibrium, a = + or - 9.8 (m/s)/s, Free Fall, no forces act on an object other than the gravitional force that makes the object fall, Projectiles, an object in free fall that have a nonzero horizontal velocity component, motion of a projectile takes place in a vertical plane, Angle of elevation, is the angle of the initial velocity above the horizontal, Trajectory, path, Air resistance, drag, increases as the speed increases, terminal velocity, velocity at which equilibruim occurs (drag force equals in magnitude to the weight but opposite in direction), direction is always downward if there are no forces other than air resistance and gravity, terminal speed, magnitude of terminal velocity, As the velocity approaches the terminal velocity, the acceleration gets smaller and smaller, The acceleration is zero when the object falls at its terminal velocity, depends on objects size, shape, and mass, a = constant, Special case, a = const. (when net forces act!), Between the "kinks" (corners), change in motion, During the "bowls" (parabolic motion), Change in acceleration, Bowl up, Bowl down

Kinematical Equations of Motion for 1-D, v = (vo) + at, x = (xo) + (vo)t + 1/2 * a(t*t), v*v = (vo*vo) + 2a (xf - xo)

Problem solving techniques for kinematics, Wants / Knowns, Draw picture, Set coordinate axes and assign symbols to numbers, Choose the correct equation(s), Solve for the variable of interest

## Words of the Day

### Mash-Up

Combining data from more than one source into a single integrated tool

### Red Herring

Something intended to divert attention from the real problem or matter at hand

### Panacea

A remedy for all difficulties

Cure-All

### Ithaca

Get to Destination

### Ne Plus Ultra

The acme, most profound degree

### Modus Operandi

Mode of operation, Process

### Forestall

To deal with or think of beforehand

anticipate