7k Forces Flashcards
What do forces do
Can change the shape,speed, or direction
What is the difference between a contact force and a non contact force
A force which affects an object from a distance is a non contact force
How do we measure forces
A newton metre
What is mass
Mass is the amount of matter which makes something up
Weight formula
Mass multiplied by 10 N
What is friction and is it useful
It is the force between two touching objects (air resistance and water resistance are types of friction )
Sometimes it is useful for things like walking however can n9t be useful when there is too much friction between axels of a cycle it won’t move
What can we do to reduce friction
Use a lubricant
What does friction produce
Heat and noise
Air and water resistance can be reduced by
Having smooth surfaces and shapes
An object will float when
The upthrust cancels its weight
Explain how something will float in terms of density
If the objects density is less than the liquid it will float
Density formula
Mass in grams divided by volume in cm cubed
Speed formula
Distance divided by time
All stationary objects have
Balanced forces
Moving objects at the same speed
Have balanced forces
An object has unbalanced forces when
It changes speed
What measures speed
A force meter
What is the thinking distance
The distance the car travels in the time between when a driver sees something on the road realised they need to stop
What is the breaking distance
The distance a car travels after the break pedal is pressed before it stops
The stopping distance is
The break distance and thinking distance sum
On distance time graph a steep slope is
Acceleration
On distance time graph a shallow slope
Is a slow speed
To find the relative motion of two objects opposite each other you
Add their speed
To work out relative motion of two objects going the same direction you
Subtract the speed of the object behind of the one in front for example ma car is going at 30 mph and a tractor behind it is going at 20 mph so car minus tractor
Non contact forces are
Gravitational pull between planets
Forces between magnets
Forces due to static electricity
