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

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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!

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Watch this video as introduction. In your own time.

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Episode 2: The Law Of Falling Bodies - The Mechanical Universe

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FREEFALL - falling under the influence of gravity only

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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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Mark Ex 1.3 - Q1,3,5,6

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INTRODUCTION TO THE PHYSICS AND GRAPHS OF BOUNCING

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INTRODUCTION TO THE PHYSICS AND GRAPHS OF BOUNCING

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BOUNCING BALL PHYSICS

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Ball bouncing in slow motion: Rubber ball

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Using Tracker:

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Use of Tracker to understand Bouncing Ball Kinematics Graphs

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With inelastic bouncing:

Ek of object after bouncing < Ek of object before bouncing

Rebound velocity after bounce < impact velocity upon bounce

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With elastic bouncing:

Ek of object after bouncing = Ek of object before bouncing

Rebound velocity after bounce = impact velocity upon bounce

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Kinematics Graph  Bouncing Ball Elastic ~xmphysics0

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With inelastic bouncing:

Ek of object after bouncing < Ek of object before bouncing

Rebound velocity after bounce < impact velocity upon bounce

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Kinematics Graph  Bouncing Ball Inelastic ~xmphysics0

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Explaining how energy is lost in inelastic collisions:

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With inelastic bouncing:

Ek of object after bouncing < Ek of object before bouncing

Rebound velocity after bounce < impact velocity upon bounce

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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.

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Episode 4: Inertia - The Mechanical Universe