projectilemotion.ppt - EIUux1.eiu.edu/~cblehman/lectures/projectilemotion.pdf · Page 1 Projectile...
Transcript of projectilemotion.ppt - EIUux1.eiu.edu/~cblehman/lectures/projectilemotion.pdf · Page 1 Projectile...
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Projectile MotionProjectile Motion
Projectile Motion
Feeding the MonkeyFeeding the Monkey(Banana Gun)(Banana Gun)
� Where does the zookeeper aim if he wants to hit the monkey?
( He knows the monkey willlet go as soon as he shoots ! )
Feeding the Monkey...Feeding the Monkey...
� If there were no gravity, simply aim
at the monkey
r = r0
r =v0t
Feeding the Monkey...Feeding the Monkey...
rr = vv0 t -1/2 gg t
2
� With gravity, still aim at the monkey! rr = r0 -
1/2 gg t2
Banana hits
monkey!
Projectile: An Object Moving Projectile: An Object Moving Solely Under Influence of GravitySolely Under Influence of Gravity Horizontally Launched ProjectileHorizontally Launched Projectile
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Projectile MotionProjectile MotionProjectile VelocitiesProjectile Velocities
Net Force in FreefallNet Force in Freefall
Horizontal
Motion
Vertical
Motion
Net Force NO
YES – force of gravity –downward
Acceleration NO
YES – “g” is downward at about 10 m/s/s
Velocity Constant
Changing by about 10 m/s each second
Independence of x & y MotionsIndependence of x & y Motions
t (s) Vy(m/s) Y (m)
0 0 0
1 10 5
2 20 20
3 30 45
4 40 80
t 10 t 5t2
X (m)
0
5
10
15
20
vxt
For Vx= 5 m/s
Projectile Launched at AngleProjectile Launched at Angle Projectile Launched at Angle Projectile Launched at Angle -- 22
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Monkey ZookeeperMonkey Zookeeper Monkey Monkey –– Zookeeper Zookeeper –– No GravityNo Gravity
Monkey Zookeeper Monkey Zookeeper -- FastFast Monkey Monkey –– Zookeeper Zookeeper -- SlowSlow
Projectile TrajectoriesProjectile Trajectories
Complementary
angles have equal
ranges
Satellite MotionSatellite Motion
�If superman threw a rock fast enough … it would orbit the earth (if there were no air resistance
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Satellite = Fast ProjectileSatellite = Fast Projectile
� Since the earth’s surface curves away from the horizontal by 5 m for every 8000 m tangent to the surface
� V = 8000 m/s = 8 km/s
Satellite PeriodsSatellite Periods
� For a satellite close to the Earth, the period (the time for a complete orbit about the Earth) is about 90 minutes.
� For higher altitudes, the orbital speed is less, distance is more, and the period is longer.
� For example, communication satellites located in orbit 5.5 Earth radii above the surface of the Earth have a period of 24 hours.
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