Newton’s Laws Flashcards
What is linear motion?
Motion in a straight or curved line, with all body parts moving the same distance at the same speed in the same direction.
What’s an example of linear motion?
A 100m athlete will travel with linear motion in a straight line during their race.
A 200m athlete will travel with linear motion in a curved line when running the bend.
What are Newton’s laws?
Physics laws
They describe the relationship between a body and the forces acting upon it, and the body’s motion in response to these forces to help us understand human movement.
What is Newton’s first law?
The law of inertia.
A force is required to change the state of motion.
What is inertia?
The resistance an object has to a change in its state of motion.
If an object is at rest, it will remain still.
If an object is moving in one direction, it will continue to do so at the same velocity, until another force acts upon it.
How does mass affect the inertia?
The bigger the mass, the larger the inertia of a body or object.
This means that more force will be needed to change its state of motion.
What’s an example of inertia?
2 rugby players running towards you.
One is a prop weighing 100kg and the other is a winger weighing 75kg, which would you prefer to stop?
The winger as they will be easier to stop because they have less inertia.
What does Newton’s first law state?
Every body continues in its state of rest or motion in a straight line, unless compelled to change that state by external forces exerted upon it.
What is Newton’s second law?
Law of acceleration. The magnitude (size) and direction of the force determines the magnitude and direction of the acceleration.
What’s the equation for Newton’s second law?
Force = mass x acceleration (F=ma)
What does the equation suggest?
If the masses involved remain constant, then acceleration is equal to the size of the force causing it.
What’s an example of the equation in sport?
To provide acceleration at the start of a sprint race, an athlete will have to apply a large force internally with their gluteals, quadriceps and gastrocnemius as they drive forward.
What is Newton’s third law?
Law of action/reaction.
For every action (force) there is an equal and opposite reaction (force).
What’s an example of Newton’s third law in sport?
At a sprint start, the athlete pushes back on the blocks as hard as possible (this is the action), and the blocks push forward on the athlete (this push forward is the reaction) and provides acceleration on the athlete.
What is a ground reaction force (GRF)?
This is the equal and opposite force exerted on a performer who applies muscular force on the ground
