KINEMATICS - HORIZONTAL & VERTICAL PROJECTILE MOTION by Lizelle Swanepoel

EQUATIONS OF MOTION

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FOR USE WHEN YOU DO BOTH HORIZONTAL OR VERTICAL MOTION PROBLEMS:

uvast variables

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FOCUS POINTS FOR KINEMATICS

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1. KINEMATICS – HORIZONTAL

• Definitions asked – will guide you into the questions which follow.
• Make a summary and a sketch of applicable given information.
• ALWAYS write the formula which you are going to use in a sub-question before substituting the relevant values.
• Take note that equations of motion can only be used during constant acceleration or motion in a straight line.
• MENTION THE DIRECTION IN YOUR EXPLANATORY SENTENCE, WITH A POSITIVE FINAL ANSWER, WHEN CALCULATING A VECTOR QUANTITY.
• Graphs:

The gradient or area enclosed of the graph provide useful information.
x- and y-intercepts provide you with useful information - initial velocity, final velocity etc.
Maximum and minimum values and turning around points are important.
Average and instantaneous gradients are calculated in different ways.
Whenever you use values from a graph, they must be on the line of best fit.
Indicate the values used on your graph by circling them.
Data points on a graph are drawn with crosses, not dots!

2. KINEMATICS – VERTICAL

• Definitions asked – will guide you into the questions which follow.
• Make a summary and sketch of applicable given information.
• ALWAYS write down the formula which you are going to use in a sub-question before substituting the relevant values.
• Equations of motion can only be used during constant acceleration or motion in a straight line.
• When an object is in free-fall, close to the surface of the earth, the object will experience a constant acceleration of 9,8 m.s^-2 downward. This is true even if the object has a periodic velocity of 0 m.s^-1 at its turning (highest) point.
• The acceleration during a bounce is NOT equal to 9,8 m.s^-2 .
• MENTION THE DIRECTION IN YOUR EXPLANATORY SENTENCE, WITH A
POSITIVE FINAL ANSWER, WHEN CALCULATING A VECTOR QUANTITY.
• Graphs:

The gradient or area enclosed of the graph provide useful information.
x- and y-intercepts provide you with useful information - initial velocity, final velocity, etc.
Maximum and minimum values and turning (highest) points are important.
Average and instantaneous gradients are calculated in different ways.
Whenever you use values from a graph, they must sit on the line of best fit.
Indicate the values used on your graph by circling them.
Data points on a graph are drawn with crosses, not dots!

HORIZONTAL MOTION

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VERTICAL MOTION

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FREEFALL - falling under the influence of gravity only

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THE LAW OF FALLING BODIES:
In a vacuum, all bodies fall with the same constant acceleration.

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4 MAIN SCENARIOS OF VERTICAL MOTION

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SIGNS OF VARIABLES

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TYPES OF PROBLEMS ON VERTICAL PROJECTILE MOTION

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EXAMPLES

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SOLUTION

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HOT AIR BALLOON EXAMPLE

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ANSWER

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Answers to first exercises in Booklet

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Exercise 1.2

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Homework Answers - EXERCISE 1.3

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Mark Ex 1.3 - Q1,3,5,6

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BOUNCING OBJECTS

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BOUNCING BALL GRAPHS

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Using Tracker:

Inelastic bouncing

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With inelastic bouncing:

E_k of object after bouncing < E_k of object before bouncing
Rebound velocity after bounce < impact velocity upon bounce

Before the drop

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After the drop and first bounce

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ELASTIC BOUNCING

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With elastic bouncing:

E_k of object after bouncing = E_k of object before bouncing
Rebound velocity after bounce = impact velocity upon bounce

INELASTIC BOUNCING

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With inelastic bouncing:

E_k of object after bouncing < E_k of object before bouncing
Rebound velocity after bounce < impact velocity upon bounce

STACKED BOUNCING BALLS 🏀

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INELASTIC BOUNCING

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With inelastic bouncing:

E_k of object after bouncing < E_k of object before bouncing
Rebound velocity after bounce < impact velocity upon bounce

BALL BOUNCE PROBLEM

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HOW TO GRAPH
Choose down as positive direction:

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1.3.8 Draw the v-t graph for the motion of the ball.
Down is positive direction:

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1.3.9 Calculate the displacement of the ball.
Down is positive direction:

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1.3.10 Draw the position-time graph for the motion of the ball.
Down is positive direction:

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1.3.11 Use the ground as reference position, and re-draw the position-time graph.

BOUNCING BALL PROBLEM

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ANSWERS TO GRAPHING QUESTIONS

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Galileo and Falling Bodies

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The Law of Falling Bodies

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Watch this video as introduction. In your own time.

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HOW TO USE THIS PADLET

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Magnify posts by clicking ctrl+ on your computer
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Watch all posted videos in the Padlet to assist learning this section
Watch all my posted teaching videos on Classroom as overview of each topic
Download PhET's DC Kit virtual Lab to physically build circuits yourself given to you in harder problems to assist understanding of circuit rules.

Application of x,v,a gradient and area under graph

lizellexs — 2020-12-27 11:36:38 UTC