Have you ever played Sepak Takraw? Have you ever wondered how you could control the path of the rattan ball better? Is there any science behind the path that the rattan ball takes after you've kicked it?
The answer is YES!!! Projectile motion is involved while playing the Sepak Takraw. If you aspire to be a professional Sepak Takraw player, this post is a MUST READ!!
Sepak Takraw also known as kick volleyball is a sport native to the Malay-Thai Peninsula. It is a popular sport in South-east Asia. The difference between sepak takraw and the similar sport of volleyball is in its use of a rattan ball and players are allowed only to use their feet, knee, chest and head to touch the ball.
The physics behind Sepak Takraw is that when the rattan ball is kicked, the ball will follow a parabolic path as there is both a vertical and horizontal component of the velocity as shown in the video and pictures below:
The horizontal projectile motion is always analyzed separately from the vertical projectile motion.
Let x denote the horizontal components of the projectile motion.
Let y denote the vertical component of the projectile motion.
Assuming the ball is kicked with an initial velocity of magnitude u in a direction at angle A above the horizontal as shown below:
The formula of the various horizontal and vertical projectile motions is as shown below:
Horizontal projectile motion | Vertical projectile motion |
Initial velocity = u cos A | Initial velocity = u sin A |
Acceleration, a = 0 | Acceleration, a = - g (g = gravity) |
Time taken = t | Time taken = t |
Distance moved, x = ut cos A + ½ at2 = ut cos A | Distance moved, y = (ut sin A) + ½ at2 = (ut sin A) - ½ gt2 |
Final speed vx = u cos A + at = u cos A | Final speed vy = (u sin A) + at = (u sin A) - gt |
The horizontal velocity will always remain constant while the vertical velocity will decrease steadily at a rate of 10 m/s2 due to the gravity.
Applying Phytire Theroem, after time, t:
Hence, it can be seen that the initial velocity u and the angle A at which the rattan ball is kicked is very important for the subsequent path of the rattan ball. The following video shows the path of the rattan ball when it is kicked at various angle A.
Applet
Besides Sepak Takraw, there are also many other sports that apply the principle of projectile motion.
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