Graphs

Topic Overview The motion of an object can be represented by two types of graphs (x, v) 1) Displacement vs. Time graphs Tells you where the object is The slope (steepness) is the velocity In the graph above A is faster than B X (m) Time (s) A B

Topic Overview 1) Types of Motion for x vs. t graphs X (m) Time (s) X (m) Time (s) X (m) Time (s) Not moving because the position does not change Constant velocity because the slope does not change (linear) Accelerating because it is a curve

Topic Overview 2) Velocity vs Time graphs Tells you how fast the object is moving Slope of the line = Acceleration Area under curve = Displacement v (m/s) (s) 0

Topic Overview 2) Velocity vs. Time graphs Constant speed because the value for velocity does not change Speeding up because the value of the velocity is moving away from zero v (m/s) (s) 0 v (m/s) (s) 0 v (m/s) (s) 0 Slowing down because the value of the velocity is moving toward zero

Example Question-2

Example Question-2 Solution

Calculations with graphs!:

Example Question-1 Displacement: Difference between y value Average Speed: Slope between 2 time points Instantaneous speed: Slope at 1 time point (TANGENT)

Example Question-1 Solution

Example Question-2 What is the average speed from 0-6 seconds?

Example Question-2 Solution What is the average speed from 0-6 seconds? Average is the slope between 2 points Slope = (4 – 0) = 0.66m/s (6 – 0)

Example Question-3 What is the displacement from 1-4 seconds?

Example Question-3 Solution Position increased (+) from 2m to 4m Answer: 4 – 2 = 2m

Equilibrium Forces

Topic Overview A force is a push or a pull applied to an object. A net Force (F net ) is the sum of all the forces on an object (direction determines + or -) F net = 6N to the right

Isaac Newton has laws that describe the motion of object (I will go out of order….) 3 rd Law: Equal and Opposite ▫ For every action, there is an equal and opposite reaction. ▫ “Things push back”

1 st Law: Law of inertia ▫ An object at rest will stay at rest unless acted on by an outside force ▫ An object in motion will stay in motion unless acted on by an outside force. ▫ Inertia: The amount of mass an object has ▫ More inertia = more mass = Harder to move

Topic Overview The first law is basically the law of EQUILIBRIUM. When an object is in equilibrium, the net force equals zero Equilibrium  Fnet = 0 Up = Down Forces Left = Right Forces Objects in equilibrium can either be at rest or be moving with constant velocity

Sample Problem What is the magnitude and direction of the force that will establish equilibrium on the block?