Topic 10 friction and drag HL Flashcards
What is friction
Friction occurs when two surfaces are in contact and acts opposite to relative motion
What is the relationship between coefficient of friction and friction
The higher the coefficient of friction the more friction there is. (Skates on ice have lower coefficient of friction than studs on football pitch)
Define coefficient of friction and what it depends on?
Coefficient of friction is the ration of the friction between two surfaces. It’s affected by the material in contact.
Standard deviation
Shows the spread/variation of results around the mean
explain how a gymnast will manipulate their moment of inertia when doing a flip (3)
-High moment of inertia = low angular velocity
-gymnast tuck in - lower moment of inertia - increases angularvelocity
- before landing - gymnasts tucks outwards - slowing the rotation and increasing moment of inertia
Explain the differences between static and dynamic friction (3)
static: maximum possible of frictional force before an object moves
dynamic: ammount of force required to overcome static friction, causing movement
More force is required to overcome static friction and dynamic
Newton’s first law
An object will remain at rest unless acted by an external force
bernouli’s law (5)
- Bernouli’s law explains how relative air pressure around a ball means that it will experience a lift force and travle further
- the (back) spin of a projectile means that it will experience low pressure at the top and high pressure at bottom
- ball is attracted to area of low pressure, top of the ball, will experience lift
- lift is perpendicular to airflow
- faster the ball travels greater the lift
Types of drag and how they can be reduced in swimming
Surface drag: The outer surface catches a layer of fluid
Swimsuit (more smooth)
form drag: reaction of a fluid when body pushes against it
improve technique/form
wave drag: displacement of fluid as a body moves through its surface
swimming underwater
drag
force acting opposite of the motion of an object through a fluid