Kinetic Parameters Flashcards
What are the five types of force ?
Air Resistance, Gravity, Magnetism, Friction, and Water Resistance.
What is Friction ?
Friction is the force that acts whenever one body moves or tends to move against the surface of another and opposes the intended motion.
What are the three types of friction ?
Static (or limiting)
Sliding (or kinetic)
Rolling
Fact Card !
Pressure is defined as the force per unit area.
During sporting activities in order to minimise the pressure during a collision the force of the impact should be spread over a large area.
What is Work ?
The work done on a body by a force is equal to the product of its magnitude and the distance that the body moves in the direction of the force.
Fact Card !
Kinetic Energy: The energy a body has as a result
of its motion.
Potential Energy: The energy a body has as a result of its position.
Strain (Elastic) Energy: Important in human movement and based on the properties of tissues.
Other forms are heat, sound, chemical, electrical, radiant and nuclear.
What happens in terms of energy when you throw a ball into the air ?
During airborne phases: kinetic energy decreases and potential energy increases during the upward phase, and the reverse occurs during the downward phase.
At the point of release the body has zero potential energy and its kinetic energy is maximum. At the peak of the flight the kinetic energy is zero while the potential is maximum. On the way down the reverse occurs.
Work by our muscles (Fact Card)
Work is what we do when we move. Our muscles do positive work when they contract concentrically, and negative work when they contract eccentrically.
The more work a muscle does, the more energy is generated or absorbed.
When our muscles do positive work, they require energy that normally comes from sources like glycogen. By contrast, muscles doing negative work store energy in the form of elastic energy.
What is the difference between power and strengh ?
Power depends on how quickly your muscles can generate force and is based on muscle size and proportion of fast-twitch fibres.
Power Output (Fact Card)
In order to have a power output (and therefore to do useful work), a certain proportion of force and velocity have to occur simultaneously.
If you think about pedalling on a bicycle, you will notice that using a low gear when travelling quickly has little or no effect on acceleration, because the forces applied are low and pedalling velocity is high.
Likewise, pedalling in a high gear when cycling uphill is difficult because the resistive force is high in comparison with the speed of pedalling. It is therefore important in cycling that an appropriate gear is chosen to ensure maximum power output.
Impulse Momentum (Fact Card)
Production of a high force does not always result in a large amount of positive or negative acceleration. The amount of time spent applying that force is also of importance as if you hit the brakes of a car for a second or 10 seconds the accelleration output would differ.
