Javelin
Nicole
Uyen
Hypothesis: Does the size and strength matter when competing
in the javelin throw?
History of the
javelin: It is believed that the first
javelin thrower was Hercules, son of Zeus. The javelin throw event
was first introduced in the 708 BC Games. It was composed of two
events: throwing at a target and throwing for distance. When they
were throwing for distance, they were using the same principles
that we use today. For throwing at a target, they would ride the
horse and throw at a target when the horse was in motion. Riding
the horse and tossing the Javelin required incredible coordination
from the rider. The first javelins were made of olive wood that
weighted 400 grams and were 2.3 to 2.4 meters long. In 1780 the
javelin was changed. The length changed from 2.3 meters to 2.6
meters long and the weight changed to 800 grams. Instead of using
olive wood they used hickory wood. Then in 1953 Franklin Held
invented the hollow javelin that gave the javelin 27% more surface
area therefore making the javelin flight much longer. When doing
this it made the javelin land horizontally. From the time of Hercules
to the present, the sport of javelin has changed many times but
the participants are still looking strong. As we improve technology
so is the design of the javelin, we went from woods to metals.
Physics of throwing:
Here are the basic principles of the
javelin throw. First, assume there are aerodynamic forces involved
in the throw. Aerodynamic's are a big consideration when it comes
to throwing the javelin.
Variables:
H:Height of release is the distance from the ground
to the place where the javelin leaves the hand.
D: Distance thrown. Assume that the distance thrown
is equal to the measuring distance. You will need to assume that
the thrower releases the javelin exactly above the origin of measurement.
When measuring the javelin, you will need to take or add at least
a meter or two for the actual measurement.
V: Velocity of the javelin at release, which can e separated
into its horizontal and vertical components: Vx and Vy, respectively.
N: Angle of release.
T: Is a time measurement. t=0 at moment of release.
The acceleration of the javelin, while in
flight, is always -9.8 meters/second squared; the act of gravity
on the Javelin. Gravity is always acting vertically; there is
no horizontal deceleration in the absence of aerodynamic forces.
If acceleration is always -9.8m/s^2, we
can describe the vertical velocity of the implement at any time,
t, as: Vy=Vsin(n)-9.8t. In other words, the vertical velocity
decreases by 9.8m/s every second.
The horizontal velocity is constant while
the javelin is in flight. It is Vcos(n).
The vertical position si x=Vx(t).
To describe the relationship between angle
of release, release velocity, and distance thrown. First, you
can solve for the time, t', at which the javelin lands. Substituting,
set 9.8t^2-Vsin(n)-h=0, and solve for t. Using the quadratic formula,
t'=(-9.8+sqrt[(Vsin(n))62 + 39.2h])/19.6.
Distance thrown, d=Vcos(n)t'; d=Vcos(n){-9.8+sqrt[(Vsin(n))^2
+ 39.2h])/19.6).
So this is the relationship of distance
thrown (d), angle of release (n), height of release (h), and release
velocity (V).
Procedure:
* Went to the track meet to video tape the
javelin throwers at Clackamas High School.
* Then we set up the tripod right next to
the throwers and video taped their throws.
* We decided what throwers we wanted to
put onto the computer.
* Then we took the video to physics and
put it into the computer digitally using Avid Cinema.
* We collected data from the video using
the program Video Point.
* Made a data table comparing the differences.
* Entered the data into our homepage.
* We did our research on the internet, encyclopedia
and in magazines.
* We then gathered graphics and video off
the internet.
* We put together our information, data,
and everything into our homepage.
Records:
Technique:
Written
by: Doug Medernach, UofS / STFC Throws Coach
NOTE: This is written for a right handed
thrower. Lefties should reverse left and right.
"Competition
Rules and Regulations"
-> runway length has no limit.
-> the throwing sector is 29deg. (make
a triangle with 2-20m sides and a 10m base to get 29deg.).
-> fault line should be placed where
the distance between the sides of the triangle is 4m. The fault
line is extended 75cm past the triangle.
-> implement weights: female - 600g male
- pee wee to midget (600g) juvenille and up (800g).
-> a throw must land within the sector
lines.
-> the thrower may not: step on or over
the foul line turn their back to the throwing area without permission
exit the runway before the implement has landed take more than
1.5 min. to throw.
-> once the javelin has ended the thrower
must exit the side of the runway, without crossing the fault line
which extends in definately.
-> for a throw to count, the steel tip
must land first and must leave a mark.
-> when measuring, pull the tape thru
the back of the fault line and read the distance, to the nearest
even cm, from the inside of the fault line.
1) Grip
a) Finnish grip
(my personal choice)
-> the index finger rests at the top
of the cord and wraps around.
-> the thumb goes straight along the
javelin.
-> the javelin rests diagonally across
the palm.
-> the other 3 fingers wrap firmly around
the cord.
b) American grip
-> similar to the Finnish grip except
that the middle finger wraps around the top of the cord and the
index finger is wrapped just above the cord.
c) Fork Grip
-> form a V between the index and middle
fingers, which are bent.
-> the lower 2 fingers wrap tightly along
the cord.
-> the thumb lies straight along the
javelin.
2) "Target
Throw"
-> stand with hips and shoulders forward.
-> hold the javelin directly over your
ear, just higher than your head.
-> aim the tip downwards, at a point
about 5-10m away.
-> throw the javelin by rotating the
shoulder forward and a hard snap of the wrist.
-> good warmup drill, even for advanced
throwers.
-> shows proper release technique Variations.
-> for younger kids, create a target
shooting game.
-> start the target throw at 5m and over
time progress to 10, 15,20 and so on until the distance is no
longer increasing.
3) "Stand
Throw"
-> start with your feet about shoulder
width apart,front foot facing forward, back foot facing sideways
(Note: for right handed throwers, the back foot is the right foot,
for lefies its left) "Withdraw the javelin" -> arm
extends out and the shoulders turn side ways, while the hips remain
facing forward.
-> arm is kept relaxed, elbow slightly
bent, hand higher than the elbow, elbow higher than the shoulder.
->check to make sure the javelin is in
line with the direction of the throw, then look forward. The javelin
should be visable out of the corner of your eye.
-> the back leg should be slightly bent,
front leg relatively straight.
-> start the throw by driving the hips
forward.
-> it is imperitive that the javelin
is moved in a straight line in the direction of the throw.
-> the "Armstrike" brings the
javelin from the withdrawn position to the target throw position,
this time with the tip facing up (30-40deg.).
-> to do this the elbow must bend and
the shoulders must turn forward, then rotate the shoulder, flick
the wrist and see where it lands.
4) Impulse Step
and Throw
5) Short Approach
6) Adding a Runup
TROUBLESHOOTING
1)Improper withdrwal
of the javelin: It is common for throwers
to withdraw the javelin either out to one side or too low which
results in too great an angle of release. This could cause the
tip to hit the ground during layback. Teach the athlete to see
the javelin out of the corner of their eye and get a feel for
what they should see when the javelin is withdrawn correctly.
If this doesn't work, return to standing throws.
2) Partial extension
of throwing arm during withdrawl: We
want to get the arm extended as far back as possible to allow
more time to apply force to the javelin. If this is due to a lack
of flexibility then a variety of stretching and range of motion
exercises should be used.
3) Insufficient
lay back:Failure to achieve sufficient
layback can result in some/all of the following: less time to
apply force, failure to hit the C position, improper leg drive,
and unbalanced delivery.
4) Narrow Base: This is when the athlete fails to extend their left
leg far enough. This leads to an ineffective hip drive therby
reducing the amount of force the thrower can apply to the javelin.
5) Incorrect delivery:
A common fault on delivery is over-rotation
-->turning away from the direction of the throw before releasing
the javelin. This results in the javelin missing its correct line
of flight. The cause is usually a turn of the head away from the
throw (loss of focal) or a break of the block leg
Data:
Graph Trial #1:
Graph Trial #2:
Interviews:
We put these questions
on the internet:
1. How many different
ways can you throw the javelin?
One
2. How does the
design of the javelin effect the way the javelin travels?
Lots of ways. 7.. High up
3. How many steps
do you use when throwing the javelin?
12
4. Does the size
matter when throwing the javelin?
Yes 800 g
5. What is your
normal workout?
3 times a week
6. Do you have
to be strong to throw the javelin?
Yes it helps but speed is needed also. (fast
arm)
Conclusion: In conclusion our data and our hypothesis are correct.
Size plays a role in the distance of the throw. For instance,
lets say a 5'5", 130 lbs.player is throwing against and 6'1"
190 lbs player. Of course the 6'1" player is going to cream
the 5'5" player because of the extra weight (strength) and
the height advantage. The taller player also has a larger wing
span.
Bibliography
Internet sites: