Chapter-3Falling Objects and Projectile

Motion

Outline:Acceleration due to gravityFalling objectProjectile motion

Overview:Explore how objects move under the influence of gravity close to the surface of the earth.

Falling ObjectsWhy objects fall to the ground when released?

When you drop objects of different sizes and weights, do they reach the ground at the same time? (Click the link below)

http://www.teachersdomain.org/resource/phy03.sci.phys.mfw.galmoon/

Measuring the acceleration due to gravity for Earth: 9.8 m/s2

Falling Object: Velocity and Distance

Spread Sheet (Excel) Calculations v=v0 + at d=v0t+1/2 at2

t (s) v (m/s) d (m)0 0 01 9.8 4.92 19.6 19.63 29.4 44.14 39.2 78.45 49 122.56 58.8 176.47 68.6 240.18 78.4 313.69 88.2 396.9

10 98 49011 107.8 592.912 117.6 705.613 127.4 828.114 137.2 960.415 147 1102.516 156.8 1254.417 166.6 1416.118 176.4 1587.619 186.2 1768.920 196 1960

y = 9.8x

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0 5 10 15 20 25

Time (s)

V (

m/s

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0 5 10 15 20 25

t (s)

d (

m)

Reaction Time Experiment

Throwing up a ball:Velocity and Distance

Q: A ball is thrown straight upward and then returns to the Earth. Does the acceleration change during this motion?

Throwing up a ball: Velocity VS. Time graph

Projectile Motion:A Cartoon Coyote Falling off a Cliff

We need to consider the horizontal and vertical motions separately in projectile motions. Time is the same for both motions.

Horizontal and Vertical motions

Q: What determines the time of flight?

A: Vertical motion

Practice Sample Exercise in example box 3.4

Angle for maximum Range

http://phet.colorado.edu/simulations/sims.php?sim=Projectile_Motion

Go to the above website and determine the angle for maximum range by firing at different angles. ______________