# Physics 5 Flashcards

What force us created when a object is pulled along the ground?

Friction

How can friction be reduced

- Using rollers or wheels

- Having a smooth surface

What are the types of forces

- friction
- weight (gravity)
- upthrust
- magnetic
- electrostatic
- nuclear
- thrust

In what unit are forces measured

N -> newtons

Air resistance and water resistance are forms of….

Drag

When does the drag force increase?

When speed increases

Top speed

The maximum speed a object can go

Energy stores

- kinetic
- chemical
- thermal
- gravitational potential
- elastic potential
- sound

Law of conservation of energy

Energy is never created or destroyed only transferred or stored

Equation of speed

Speed= distance

—————–

time

Mean (average) speed

total distance

———————

total time taken

steep line on distance-time graphs

Means you are travelling quickly

Horizontal line on distance-time graph

Not moving at all

Relative speed

Add= if you are on a train and the train is moving at 50km/h and you move the same direction at 3km/h your relative speed is 53km/h

Subtract= if you are on a train which is moving at 50km/h and you move in the opposite direction at 3km/h your relative speed is 47km/h

Multiply=if two trains are traveling at 50km/h towards each other the are moving at a relative speed of 100km/h

Moment equation

Moment of the force = force x perpendicular distance from pivot

(N m) (N) (m)

Lever

A lever is a long bar that turns around the pivot

Pivot

The point where the object turns

Synonym for pivot

Fulcrum

Rule to move load

The longer the lever the easier it is to move the load

What does the lever do

Acts like a force multiplier if the effort distance is larger than the load distance

In equilibrium

When the forces are balanced

What are most machines used for

Use smaller force to move a object

Name 3 simple machines

- lever
- ramp
- pulley

Why are Ramos efficient

It needs less force to push a object up a ramp than it does to lift it directly