Topic 10 friction and drag HL Flashcards

1
Q

What is friction

A

Friction occurs when two surfaces are in contact and acts opposite to relative motion

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2
Q

What is the relationship between coefficient of friction and friction

A

The higher the coefficient of friction the more friction there is. (Skates on ice have lower coefficient of friction than studs on football pitch)

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3
Q

Define coefficient of friction and what it depends on?

A

Coefficient of friction is the ration of the friction between two surfaces. It’s affected by the material in contact.

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4
Q

Standard deviation

A

Shows the spread/variation of results around the mean

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5
Q

explain how a gymnast will manipulate their moment of inertia when doing a flip (3)

A

-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

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6
Q

Explain the differences between static and dynamic friction (3)

A

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

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7
Q

Newton’s first law

A

An object will remain at rest unless acted by an external force

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8
Q

bernouli’s law (5)

A
  • 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
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9
Q

Types of drag and how they can be reduced in swimming

A

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

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10
Q

drag

A

force acting opposite of the motion of an object through a fluid

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