Final forces for HS

Vector quantity

Quantities with a magnitude and direction

Scalar quantity

Quantities with a magnitude but no direction

Position

Location, depends on reference frame

Often referred to as x

Vector quantity

Velocity

How quickly a position changes

V = change in position over time take

Vector quantity

Speed

How quickly the distance is travelled

Speed = distance/time

Scalar quantity

Measured in meters per second

Acceleration

Rate of change in velocity

Acceleration = change in velocity / time taken

Measured in meters per second squared (meters per second per second)

Vector quantity

Encompasses speeding up and slowing down as well as changing directions

When acceleration is a positive number

The object is speeding up or changing direction

When acceleration is a negative number

The object is slowing down

When acceleration is 0

Object is at a constant speed or at rest

What is the oil drop diagram?

The oil drop diagram is a series of dots that show an object’s position at equal time intervals

What does the spacing for oil drops indicate

The oil drops stay evenly spaced when an object is at rest

The oil drops get progressively closer together when an object is slowing down

The oil drops get progressively further apart when an object is speeding up

What is an applied force (Fa)

Force that one object or person exerts on another object

Can be push or pull

What is a friction force (Ff)

A force that opposes the applied force

Pull

What is a tension force (Ft)

A force that is transmitted through an object when it is stretched tight by forces acting from opposite ends

Pull

What is a gravitational force (Fg)

The force of gravity pulling the object to earth

Pull

What is a normal force (Fn)

The support force exerted by a surface on an object that is resting on it

Acts perpendicular to the surface

Normal in maths or physics means perpendicular

Push

What is thrust (Ft)

Force generated when you push something in the opposite direction

Push

What is drag (Fd)

Force generated due to the atoms/molecules/particles of a fluid hitting objects (push)

Similar to friction as it opposes motion

Also called air resistance, if the fluid is air

What is buoyant force (Fb)

Force generated when an object is submerged in fluid

Pushes against gravity

Also generated in the air but often too weak to affect objects

What is lift (Fl)

Force that is generated by the speed at which fluid flows over/under it

The faster the fluid, the higher the lift

Push

What are free body diagrams used for?

Conveying all the forces acting upon an object

What is the unit of force?

Newton (N)

Sum of force/net force = nonzero

Unbalanced forces, object will accelerate

Sum of force/net force = zero

Balanced forces, object will remain at rest

What is the law on inertia

Objects at rest will remain at rest until acted upon by an unbalanced force

Objects in motion will remain in motion at the same velocity until acted upon by an unbalanced force

Equation for Acceleration

Net force/Mass