UNIT 1 – AREA OF STUDY 2BIOMECHANICAL MOVEMENT

PRINCIPLES

ON THE MOVE MOMENTUM

WARM UP QUESTIONSThese questions relate to our last area on force production.

1. State each of Newton’s three laws and demonstrate your understanding of each law by using a sporting example:

2. Using Newton’s second law of motion, explain why a medicine ball will not move as quickly as a basketball when they are both thrown with the same force:

3 Provide three examples of action and reaction forces in sport:

GET OUT OF MY WAY!• What does it take to lay the perfect tackle?

• You are going to discover that physics and mathematics play a role in making you the perfect tackler or making sure your team matches up correctly.

MOMENTUM# Momentum is a measure of

the amount of motion that an object has.

# momentum = mass x velocity

# Momentum is important when objects collide. Every time 2 objects there is a change in momentum. Both objects will continue in the same direction of the object with the greatest momentum

MOMENTUM# If 2 objects have the same

mass but different velocities, the object with the greater velocity will have the greater momentum

# If 2 objects have the same velocity but different masses, the object with the greater mass will have the greatest momentum

THINKING THINGS THROUGH

1. What 2 factors would determine an object’s momentum?

2. Which object would be harder to stop: a volleyball that has been set up ready to be spiked or a baseball that has been struck into the outfield? Justify your answer.

3. Using the picture on the first page describing momentum calculate the momentum of both players before the collision. Which player has the greatest momentum? How can the player with the less mass increase their momentum?

ANGULAR MOMENTUM How do divers, gymnasts and skaters control

the speed of their rotations in the air?

Angular motion obeys the same principles as linear motion; however, they have a slightly different spin!

The amount of angular motion possessed by a body is known as the angular of momentum of an object.

The moment of inertia is the resistance of an object to changes in its angular motion.

Newton’s laws can also be transferred to angular motion

TORQUE Before we move on to Newton’s laws you

may want to have an understanding of torque

Eccentric forces cause an objects to rotate and move forwards.

This effect is known as torque

Torque is the tendency of an object to rotate.

Torque will cause a gymnast to rotate around a bar.

NEWTON’S LAWS OF ANGULAR MOTION

1st LAW – The angular momentum of a body remains constant unless acted upon by an external torque

2nd LAW – A torque applied to an object will produce a change in angular motion in the direction of the applied torque that is directly proportional size of the torque and inversely proportional to the moment of inertia of the object.

3rd LAW – For every torque there is an equal and opposite torque.

MOMENT OF INERTIA

Moment of inertia = mass x radius(squared)

EXAMPLES OF ANGULAR MOMENTUM

For an excellent example of angular momentum please visit the following youtube clip.

http://www.youtube.com/watch?v=4SGGAWGGu3o

SUMMATION OF MOMENTUM

When the main objective of a sport is to hit, kick or throw an object or ball as far as possible, it is important that it is released or struck with maximum velocity

By coordinating all of the body parts that are involved in the movement, athletes are able to generate maximum velocity of the hand during a throw, the foot during a kick and the club, racquet or bat during a hit. This is known as the summation of momentum.

Highly skilled performance is characterised by well-timed, coordinated movements that result in optimal velocity of the object at impact or release.

AN EXAMPLE OF SUMMATION OF MOMENTUM

Golf swings are a perfect example of the summation of momentum to produce the perfect hit.

THINKING THINGS THROUGH

1. A gymnast performs three different somersault dismounts off a beam. In which position will the moment of inertia be the greatest and in which position will rotation be the fastest?

* Pike* Tuck* Layout

2. Provide a sporting example that demonstrates the correct application of each of Newton’s three laws of angular motion.

3. How can the moment of inertia of a golf club be increased or decreased? Outline the advantages or disadvantages of selecting a longer club.

WHERE TO NOW???

You can now go on with your biomechanics booklet or complete the attached practice test.

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