Motions

Describing and Calculating Motions

Basic Definitions:

Time, Position, Displacement, Velocity and Acceleration

Part 1: Definitions

Professor Dave Explains - 7 min

Part 2: Graphical Analysis

Professor Dave Explains - 7 min

Constant Acceleration in One-Dimensional Motion - Kinematic Equations

Motion in a straight line

Use kinematic equations of motion
Solve problems involving vertical motion under gravity

Note: Tell the difference of motions with constant velocity and constant acceleration.

Advance skills:

Deriving Kinematic Equation from a graph - gradient
Deriving Kinematic Equation from a graph - area
Deriving Kinematic Equation using algebra

Applying Formulae to Solve Problems

List the known quantities, using formula symbols and SI units, and the unknown quantities.
Select the appropriate formula and if needed rearrange it so that the unknown is the subject.
Substitute the values into the formula and calculate the result.
Correct the result to the number of significant figures of the least accurate measurement used.
State the result using the formula symbol and give the unit.

1: Horizontal Motion

Professor Dave Explains - 7 min

2: Vertical Motion

Professor Dave Explains - 7 min

Motion Under Gravity

Gravitational Acceleration

BBC - 4:41

ZERO Gi

Veritasium - 7:47

Terminal Velocity and Air Resistance

Next Generation Science (2 min)

MJ's Hangtime

TED-Ed

Homework:

Physics 2 SciPad p.129-130 (Speed, velocity and acceleration)
Physics 2 SciPad p.134-135 (Kinematic Equations)
Thinking: How is the g value (9.8 or 9.81 m/s^2) measured?

Gravity Timelapse

Steve Mould - 12:45

Universal law of Gravitation!

Sabins - 6:55

Vectors and Scalars

Vectors

A vector is a quantity which has both size and direction.
A scalar quantity has just size with no direction

Vector Addition: use the "head to tail" method to get the resultant vector

Vector Subtraction: the negative of a vector is in its opposite direction

Generally, you will use Pythagoras' Theorem to get the magnitude (size) and Trigonometry (sine, cosine and tangent) to get the direction (angle) of the resultant vector.

Components of a Vector

Finding two components of a vector is called resolving a vector into components.
Horizontal (x) component: cosine
Vertical (y) component: sine

Phy2.4 Mechanics - Scalars and Vectors - web1.ppsx

Scalar and Vector Quantities

Cognito (3:09)

Vector and Scalar Quantities?

Free Animated Education (4:22)

Homework:

Physics 2 SciPad p.128 (Vectors and Scalars)
Physics 2 SciPad p.136-137, 138 (Vector addition, vector subtraction)
Physics 2 SciPad p.139-141 (Relative Velocity and River Crossings - optional)

Extension: Relative velocity

Relative velocity is the velocity of one object in relation to another object. The velocity of an object may appear to be different depending on where it is measured from (i.e. reference coordinate system).
Relative velocity involves adding and subtracting vectors.

Projectile Motion

Projectile motion

Explain projectile motion
Resolve a projectile’s velocity into components
- The horizontal component is constant velocity
- The vertical component is in constant acceleration motion (free fall).
Use velocity components to solve problems
Make calculations at any point in flight

Phet Simulation - Projectile Motion

Horizontal velocity remains constant

Demo from MIT lectures by Prof Walter Lewin

Projectile Motion & Parabolas

National Science Foundation News - Science of NFL Football

3: Projectile Motion

Professor Dave Explains - 7 min

4: Practice Problems and Strategy

Professor Dave Explains - 7 min

Homework:

Physics 2 SciPad p.142-143 (Vertical Motion Under Gravity)
Physics 2 SciPad p.144-148 (Horizontal Projectile Motion)

Circular Motion

There are three mathematical quantities that will be of primary interest to us as we analyze the motion of objects in circles.

These three quantities are speed, acceleration and force. The speed of an object moving in a circle is given by the following equation on the right:

Centripetal vs. Centrifugal force

When it comes to rotation, things get really REALLY weird... so weird, in fact, that you experience things that play tricks on your perception.

In this video, I demonstrate this by having fun on a merry-go-round.

Video produced on 9 May 2014

Centripetal Acceleration

The acceleration of an object moving in a circle can be determined by either two of the following equations on the right:

What is the unit of centripetal acceleration?
In Year 12, you don't need to know how to derive this formula.
Complete the SciPad questions on p.165-168
More details about the problem solving strategies can be found at the Physics Classroom.

Homework:

Physics 2 SciPad p.164 Centripetal Acceleration
Physics 2 SciPad p.165-168 Calculating Centripetal Acceleration
Physics 2 SciPad p.170 The Outward Moving Feeling - Centrifugal Force

Uniform Circular Motion

Did you know that centrifugal force isn't really a thing? I mean, it's a thing, it's just not real. In fact, physicists call it a "Fictitious Force." Mind blown yet?

To explore this idea further, this week Shini sits down with us to discuss centripetal force, centrifugal force, and a few other bits of physics to help us understand Uniform Circular motion.

Video produced on 12 May 2016

Report abuse