MIDTERM REVIEW

General Physics

Definition of Physics

Study of Energy and matter

SI Units

Mass – kilogram Time – seconds Length – meter

Metric Prefixes

Kilo --- one thousand (1000) Hecto --- one hundred (100) Centi --- one hundredth (.01) Milli --- one thousandth (.001)

Significant Digits

10000 0.0000540 342.15 67.00 890.02

Significant Digits

Adding and Subtracting --- go by the lowest number of digits to the right of the decimal point

67.03 – 7.045 =

Significant Digits

Multiplication and Division : go by the lowest number of sig. digits

(2.45 x 105)( 3.678 x 102)=

Conversions

120 kg = ______ g 54 km = _______ mm 120 m/s = ______ km/hr 53 cm = ______ m

Distance vs. Displacement Distance: scalar, add total

distance traveled Displacement: vector,

difference between starting and ending point

Distance vs. DisplacementA person walks 10 m

north, 5 m south, then 2 m north.

What is the displacement?

What is the distance traveled?

Graphs (General)

Slope = vertical change / horizontal change

Independent variable – manipulated by the experimenter, on the x-axis

Quadratic graph – Parabola, smooth upward curve, y is proportional to x2

Inverse graph – hyperbola

Linear graph – straight line, y and x are directly proportional

Position-time graphs

Slope = velocity Constant velocity:

Constant acceleration:

Position-time graph

At rest:

Slowing Down:

Velocity-Time Graphs

Slope = acceleration Area under the curve = displacement

A = l x wA =1/2bh

Constant velocity:

Velocity-time graphs

Constant acceleration:

Velocity

V = d/t

Acceleration

Change in velocity with time

a = Dv/Dt Vf = Vi + at

d = vit + 1/2at2

WGUMCD

At max height, velocity is 0

Vf = -Vi (Perfect Symmetry)

Free Fall

Distance is proportional to t2

all objects accelerate at the same rate regardless of mass, if air resistance is ignored

Vectors

Resultant vector – the sum of more than one vector, placed from the tail of the first vector to the tip of the last vector

A student walks 7 m east and then 5 m south, what is the displacement?

Reverse the direction of the initial vector when subtracting

Component Method

X component = hcos Y component = hsin

Newton’s First Law

Equilibrium – all forces on an object are balanced Fnet = 0object is at rest or moving with a constant velocity

Newton’s Second Law

F = ma Increase acceleration:

decrease mass and increase Force

Weight: gravitational force exerted by a body

W=mg

Newton’s Second Law

A snowflake falls with a force of 5 N downward, and experiences a frictional force of 2 N upward. What is the net force on the snowflake?

What must the frictional force on the snowflake be to make it move with a constant speed?

Newton’s Second Law

A baseball player slides into second base with a force of 25 N and experiences a frictional force of 4 N. If the player has a mass of 60 kg, what is his acceleration?

Newton’s Third Law

For every action there is an equal and opposite reaction

Incline planes

Increasing the angle increases the acceleration and speed of an object

The parallel component of the force of gravity causes an object to slide down the incline plane

Fg = mg

Fg perpendicular = Fgcos

Fg parallel = Fgsin

Incline Planes

FN = -Fg perpendicular

Fric = µFN

Fnet = Fric + Fg parallel

a = Fnet /m

Projectile Motion (general) Motion in the horizontal

direction is independent of motion in the vertical direction

Velocity in the horizontal direction is constant

Type I Projectile Motion

dy= 1/2gt2

dx= vxt

vfy = gt

Type II Projectile Motion

Range increases up to 450 (max range) and then decreases after that

Vix = Vi cos

Viy = Vi sin

Vfy = Viy + gt

dy = Viy t + 1/2gt2

dx = vxt

Vf = - Vi