Y9 forces
Home > Flashcards > Print Preview
The flashcards below were created by user
AHutson
on
FreezingBlue Flashcards. What would you like to do?

What is a moment?
The turning effect of a force

How are moments calculated?
Moment (Nm) = Force (N) x distance from pivot (m)

What is a pivot?
The point around which something turns

What is fulcrum an alternative word for?
Pivot

What is a lever?
Something that uses moments to make a task require less force (make it easier)

Name some examples of levers
 Can opener
 Scissors (especially nail scissors)
 Wheel barrow
 Crowbar
 Wheel spanner

What do we know about the anticlockwise moment and the clock wise moment if an object is not turning?
They are balanced

What are the units for force?
Newtons (N)

What are the units of distance?
Metres (m)

What are the units of moments?
Newton metres (Nm)

What is a pendulum?
An object that swings to and fro

What affects the time that a pendulum takes to make a complete swing?
The length of the pendulum (nothing else!)

What name we give to the time for a pendulum to make a complete swing (back to its starting place)?
Time Period

What unit is used to measure time?
second (s)

What unit is used to measure speed?
Metres per second (m/s)

What unit is used to measure acceleration?
Metres per second squared

What is the equation for calculating acceleration?
change in speed / time taken

Name the force that keeps objects moving in a circle
Centripetal force

In which direction does centripetal force act?
Towards the centre of the circle

What is the unit of centripetal force?
Newtons (N)

What three things affect the size of the centripetal force needed to keep an object moving in a circle?
 Radius of the circle
 Speed of the object
 Mass of the object

Does increased speed need a larger or smaller centripetal force?
Larger

If the radius of the circle increases, what effect does this have on the centripetal force needed?
It reduces

If the mass of the object increases, what effect does this have on the centripetal force needed?
Increases

What provides the centripetal force that keeps the Earth orbiting around the Sun?
Gravity

What provides the centripetal force that keeps a conker tied to a piece of string moving in a circle
The tension in the string

In which direction does air resistance act?
Opposite to the direction of travel

If the speed of an object increases, how does this affect the air resistance?
Air resistance increases

If forces are balanced what do we know about the speed of an object?
 It moves at a constant speed.
 (If it was not moving it stays not moving)

What is terminal velocity?
 The speed an object moves at when the forces acting on it are balanced.
 eg a skydiver falling when her weight and air resistance are equal

Why does opening a parachute increase air resistance?
The parachute has a large surface area

What are the two units of pressure?
or Pascals (Pa)

What is the equation to calculate pressure?

What are the units for Area ?

What is inertia a measure of?
How hard to start or stop something moving

What two things affect the inertia of an object?

When a skydiver is falling, does her weight or air resistance change as her speed changes?
Air resistance (Her weight is constant)