# Bell Ringer 1.What does the slope of this graph show? 2.What is the acceleration from 4 seconds to 6 seconds?

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Bell Ringer 1.What does the slope of this graph show? 2.What is the acceleration from 4 seconds to 6 seconds?

P H Y S I C S Objects in Free Fall and Gravity Objectives: 1)We will understand free fall, and how it is impacted by gravity 2)We will understand what forces act upon an object that is thrown up into the air

Free Fall  Motion of an object when only gravity is acting on it.

Free-fall acceleration The acceleration of an object due only to the effect of gravity

Acceleration Due to Gravity g = -9.8 m/s 2 (we’re going to use 10 m/s 2 ) Objects go 10 m/s faster each second Negative Velocity  downward movement v = 0 m/s v = -9.8 m/s v = -19.6 m/s v = -29.4 m/s v = -39.2 m/s t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s

Human Breaks Sound Barrier World Free Fall Record 10/14/2012

Position and Velocity and Free Fall t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s Position and velocity can be determined as a function of time If you know the time and position, you can determine the velocity.

Skydivers

Which drops first?

Bowling Ball and Tennis Ball

Demo All objects accelerate at a constant rate of 10 m/s 2 regardless of mass or weight 123 TIMES MORE! Bowling Ball = 7 kg Tennis ball = 0.057 kg

1 Second Challenge 1 Second in Air  “A” for the semester  No tardies, cuts or absences 1.225 m in the air to get 1 s.

Jordan From Free-Throw Line

Time in Air = 0.98 s

Objects Thrown Upwards Object thrown upwards experience the same: g = -10 m/s 2 10 m/s slower each second

Remember… When you are speeding up…  You have positive acceleration When you are slowing down…  You have negative acceleration Vector  A quantity, such as position, that has both magnitude and direction

Acceleration Due to Gravity v = 0 m/s v = +9.8 m/s v = +19.6 m/s v = +29.4 m/s v = -9.8 m/s v = -19.6 m/s v = -29.4 m/s v = -39.2 m/s Velocity Vector Acceleration “g” Vector

Velocity Direction Positive (+) value  Up Negative (-) value  Down

Peak of the Path Maximum Height Velocity = 0 m/s Returning to Initial Height: Time up = Time down Velocity up = - Velocity down

Position vs Time Velocity vs Time What is happening at the apex of the position vs time graph? What is happening in the velocity vs. time graph at the x-axis?

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