Biomechanics: Newtons laws of motion Flashcards
1
Q
What are Newtons 3 laws?
A
First law
- The law of inertia.
Second law
- The law of acceleration.
Third law
- The law of action and reaction.
2
Q
Newtons 1st Law: the Law of Inertia
A
- Inertia is the resistance an object has to a change in its state of motion.
- In order to overcome inertia, an external force must be applied.
- As mass increases so does inertia.
E.g. A football will remain on the penalty spot until it is kicked.
3
Q
Newtons 2nd Law: the Law of Acceleration
A
- States that the acceleration of an object is directly proportional to the force acting on it.
- The greater the force applied, the greater the acceleration of the object.
- Force also governs direction (Force= Mass x Acceleration (Vector))
- Once acceleration ceases the object is said to have momentum.
4
Q
Example of Newtons 2nd Law
A
- When the footballer kicks (force) the ball on the penalty spot, the acceleration of the ball (rate of change of momentum) is equal to the size of the force.
- So the harder the ball is kicked, the faster it will go in the direction the force has been applied.
5
Q
Newtons 3rd Law: the Law of Action and Reaction
A
- For every action there is an equal and opposite reaction.
- Always a pair of forces acting.
-The size of force on the first object is equal to the size of the force on the second object. - Basically there is an action force and a reaction force.
6
Q
Example of Newtons 3rd Law
A
- At a sprint start, Usain Bolt pushes back on the blocks as hard as possible (this is the action).
- As a result, the blocks push forward on Usain (this push forward is the reaction force) and provides acceleration forwards.
7
Q
Important info
A
- Mass is constant.
- Inertia is constant.
- Force governs direction (F= MA)
- Acceleration is linked to velocity which is a vector.
- Do not only mention what happens if a force is greater than the inertia of an object, but what also happens when it is not!
