FORCES Flashcards
(33 cards)
What are vector quantities?
have a magnitude and direction
What are scalar quantities?
have magnitude and no direction
What is a contact force?
when two objects have to be touching for the force to act - it is contact
What is a non-contact force?
if the objects do not need to be touching for a force to act - it is non-contact
Difference between mass and weight?
- mass is the physical matter of an object - same value anywhere in universe
- weight is force acting on an object due to gravity - gravitational field strength varies with location
How are mass and weight linked?
- increasing the mass of an object increases its weight - if you double mass - weight doubles too
- weight and mass are directly proportional
What is a resultant force?
- resultant force is the overall force on a point or object
- if you have number of forces acting at single point - replace them witth single force - resultant force
What happens if a resultant force moves an object?
- if a resultant force moves an object, work is done
- to make something move - or keep it moving if there are frictional forces - a force must be applied
- force does “work” to move the object - energy is transferred from one store to another
What does it mean if an object is in equilibirum?
if all forces acting on an object combine to give a resultant force of 0 - it is in equillibirum
Stretching compressing and bending?
- when you apply a force to an object you may cause it do stretch, compress or bend
- need more than one force acting on the object for this to happen (otherwise object would simply move in direction of applied force)
What does it mean if an object has been elastically deformed?
- if it can go back to its original shape and length after force has been removed
- objects that can be elastically deformed are called elastic objects
What does it mean if an object has been inelastically deformed?
if it doesnt return to its orginal shape and length after forced removed
How does extension and force link?
extension of stretched spring is directly proportional to load or force applied
How does extension and force link alter?
- there is a limit to amount of force you can apply to an object for the extension to keep on increasing proprtionally
- known as limit of proportionality
What is a moment?
- a force can cause an object to rotate - turning effect of a force is called its moment
- moment = force x distance
- to get maximum moment - push at right angles to spanner - pushing at any other angle means a smaller distance - smaller moment
How do levers make it easier for us to do work?
- levers increase distance from pivot at which force is applies
- since M = Fd this means less force is needed to get some moment
- make it easier to do work
How do gears transmit rotational effects?
- gears are circular discs with teeth around their edges
- their teeth interlock so that turning one causes another to turn in the opposite direction
- used to transmit the rotational effect of a force from one place to another
- different sized gears can be used to change moment of force
- larger gear turns slower than smaller gear
What is fluid pressure?
- as fluid particles move around - collide with surfaces and other particles
- they exert a force whewn thyey colline - pressure is force per unit area - particles exert a pressure
- pressure of a fluid means a force is exerted at right angles to any surface in contact with fluid
What does pressure in a liquid depend on?
What is upthrust?
How does upthrust work if an object floats?
Why does atmospheric pressure decrease with height?
What is displacement?
Difference between speed and velocity?
