Frame of Reference

http://www.archive.org/details/frames_of_reference

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Motion in a Plane

 

 

 

 

Plane - 2 dimensional surface

 

What kinds of objects have
2 dimensional motion?

 

 Objects Moving
Along the Earth's Surface

 

 

Planets around sun

 

 

Pendulums

 

 

Projectiles

 

 

 

Human Cannonball
at the 2007 State Fair of Texas  

Human_Cannon_Ball.mov

 

Projectile fired horizontally

 

Review

Object projected horizontally

 

1. Viy = ?

 

 

 

 

Viy = 0

 

 

 

2. ay = ?

 

 

 

ay = 9.8 m/s2

 

 

 

 

3. Horizontal Velocity?

(no air friction)

 

 


Horizontal Velocity
is Constant
(no air friction)
 

 

Vix = Vx = Constant

 

 

 

 

Horizontal Distance Traveled


dx = Vxt

(Memorize)


 

 

 

 

 

 

4 objects thrown horizontally,

same height,

at various speeds.

 

Compare their:

 


Viy?






Same








(Viy = 0)











ay?







Same



ay = 10 m/s2




Vy?




Same
for all




height (dy)?











Same
at all times



time spent
in air




same
 

 

 

 

 

 

 

 

 

 

All objects thrown horizontally

Which ball remains

in flight the longest?

 

June 1997 #64

 

 

 

 

Choice 4 - (greatest height)

 

 

 

 

Object is thrown horizontally,
only height
determines the time in air. 

 

 

 

 

 

Ex) A baseball is thrown horizontally from a grandstand 20 m above ground at speed of 10 m/s.


(a) How long will the ball remain in flight before reaching ground? 

 

 

Ex) A baseball is thrown horizontally from a grandstand 20 m above ground at speed of 10 m/s.

 

(a) How long will the ball remain in flight before reaching ground?

 

 

Horizontal Info Vertical Info
Vx = 10 m/s Viy = 0
(thrown horizontally)
  ay = +9.8 m/s2
  dy = 20 m
  t = ?

 

 

 

Step 3 - Substitute and Solve

 

 

 

dy = Viyt + ˝ayt2

 

 

 

20 m = 0 + ˝(9.8 m/s2)t2
 

 

 

t = 2 seconds

 

 

 

 

 

(b) What is the projectile's maximum range before it hits ground?

 

 

 

(b) What is the projectile's maximum range before it hits ground?

 

 

 

 

 

Range?

 

 

 

 

 


Range (dx)

 

 

 


Horizontal Vertical
Vx = 10 m/s Viy = 0
(thrown horizontally)
dx = ? ay = +9.8 m/s2
t = 2 sec dy = 20 m
  t = 2 sec

 

 

 

Range

 

 

Horizontal Displacement (dx)

 

 

 

dx =Vxt

 

 

 

 

= (10m/s)2 secs

 

 

 

= 20 m

 

| Dartfish |

School blocks YouTube?

| Onsite |

 

Review

Which velocity is constant for all spheres?.

 

 

 

 

 

 Vx

 

 

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