What you know about math?

 

 

 

 


 

 

Projectile Motion
St. Mary's H.S. Physics

 

 

 

 

 

Projectile

Where Vix = 25 m/s

Viy = 40 m/s

t
(sec)
Vx
(m/s)
Vy
(m/s)
0 25 40
1 25 30
2 25 20
3 25 10
4 25 0
(peak)
5 25 -10
6 25 -20
7 25 -30
8 25 -40

 

 

A projectile is fired at an angle q and a velocity V. The object returns to level ground.

 

Express the time it takes for the object to hit the ground in terms of V, q and any other relevant variables

 

Viy = Visinq

Vfy = -Visinq

 

 

Vfy = Viy + at

 

-Visinq = Visinq - gt

 


Total time - Level Ground
 

t = (2Visin
q)/g

 

4. Word Problems

 

www.sihunt.co.uk Russian long jumper Tayana Lebedeva performs a
double hitch action in the 2007 world finals in Osaka Japan.

 

Ex) An athlete doing a running jump leaves ground at an angle of 25.° and a velocity of 10. m/s.

(a) How long does it take athlete to reach her maximum height?

 

                   

 

 

Viy = VisinӨ

 

 

 = (10. m/s)sin25.

 

 

 

= 4.2 m/s up

 

 

 

X Y
t = ? Viy = 4.2 m/s
(from before)
 
t  =  ?

  Vfy= 0
(peak)
 
ay = -9.8 m/s2

 

 

Vf = Vi + at

 

 

0 =4.2 m/s+(-9.8 m/s2)t

 

 

(subtract 4.2 m/s from both sides)

 

- 4.2 m/s = (-10. m/s2)t

 

 

 

(- 4.2 m/s)/(-10. m/s2) = t

 

 

 

t = .42 secs
 to reach peak

 

 

(b) How far did she jump?

 

 

On level ground

Total time =
double
peak time

 

 

 

Entire Jump:

 


Total Time = .84 seconds

 

 

 

 

 

 

dx = ?

 

 

dx = ?

t = .86 sec

 

dx = Vxt

 

 

(Must find Vx first)

 

Vx = VcosӨ

 

 

Vx = (10. m/s)cos25.

 

Vx = 9.1 m/s

 

 

 

dx = 9.1 m/s(.84 sec)

 

 

 

dx = 7.6 m

 

 

 

 

[AP]

 

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