What goes up must go down!

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Prepared by: Darwin P. Paran

Falling Bodies

Free Fall

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Gravity

• The attraction due to gravitation

that the Earth exerts on or near its

surface

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Christian Huygens• First one to

determine themagnitude of gravityfrom the swing of thependulum using a rulerand a good timepiece.

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The magnitude of gravity is

9.8𝑚

𝑠2

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• In the late 16th century, it was believed that heavier objects fall first to the ground than the lighter ones.

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Galileo • Proved that

regardless of weight and air resistance, the rate of fall of all falling bodies are the same.

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Experiment of Galileo Materials: metal ball, inclined plane, and a water timer

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How can we measure the distance covered and final velocity of a

falling body?

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Displacement of Falling Bodies

𝑑𝑦 = 𝑣𝑦𝑜𝑡 +𝑔𝑡2

2Where:

dy is displacement

vyo is initial velocity

g is gravity ( 9.8m/s2)

t is time interval

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Velocity of Falling Bodies

𝑣𝑦𝑓 = 𝑣𝑦𝑜 + 𝑔𝑡

Where vyf is final velocity.

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𝑣𝑦𝑜

𝑣𝑦𝑓

𝑑𝑦

Y

X

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Sample Problem:• The time a male bungee jumper is

freely falling is 1.5 seconds. – What is the velocity of the jumper at

the end of 1.5 seconds?

– How far does he fall?

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DISTANCE

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Given:

• vi = 0

• t = 1.5 s g = 9.8 m/s2

• 𝑣𝑓 = 𝑣𝑖 + 𝑔𝑡

• vf = 0 + (9.8m/s2)(1.5s)

• vf = 14.7 m/s or 15 m/s

• 𝑑 = 𝑣𝑖𝑡 +𝑔𝑡2

2

• d = (0)(1.5s) + (9.8 m/s2)(1.5s)2/2

• d = 11.025m or 11 m

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Reaction Time

• The time between stimulus and response.

• Measure your reaction time. ..\Activities\My Reaction Time.pdf

• Challenge your reaction time through paper bill challenge. (catch me if you can)

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Quiz: ¼ sheet of paper1. A rock fell from a cliff and reaches

the ground after 5 seconds. Compute the:

a. distance or height of the cliff to the ground?

b. final velocity of the rock before reaching the ground.

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Quiz: ¼ sheet of paper1. A ball is dropped from the 2nd floor

of a building and reached the ground after 0.98 second. Compute the:

a. distance or height

b. final velocity of the ball

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