chapter 8 - forces in balance Flashcards
what is scalar quantity?
a quantity that only has a size (magnitude) but has no direction
what is a vector quantity?
a quantity that has both a size and direction
what is a force?
a push or pull that acts on an object due to the interaction with another object
is force a vector or scalar quantity?
a vector quantity, because it has a direction
what is a contact force?
a force that arises when objects are physically touching (friction, air resistance, tension, normal contact force)
what is a non-contact force?
a force that arises when objects are physically separated (gravitational, electrostatic, magnetic)
whats the same about the interaction pair of forces when two objects interact with each other?
the forces are the same size
whats different about the interaction pair of forces when two objects interact with each other?
the forces are in opposite directions
size of resultant force on an object if the forces on it are balanced?
zero
name of the force acting on an object due to gravity?
weight
what instrument can be used to measure the weight of an object?
a newtonmeter
what is the centre of mass?
the point through which the weight of an object can be considered to act
what does newtons first law say?
the velocity of an object will only change if a resultant force is acting on it
what is the resultant force on an object moving at a steady speed in a straight line?
zero
what will an object experience if the resultant force on it is not zero?
an acceleration / change in velocity
what does newtons third law say?
when two objects interact they exert equal and opposite forces on eachother
what is scalar?
have a magnitude
what is a vector?
has a magnitude and direction
vectors VS scalars
vectors -
- velocity
- weight
- acceleration
- force
- gfs (gravitational field)
scalars -
- speed
- mass
- energy
whats the equation linking force mass and acceleration?
F = M x A force = mass x acceleration
what is the centre of mass?
the point at which all mass is considered to act and therefore the point at which gravity is considered to act
what is an irregular object?
- suspend object, draw a ijne straight down from the pivot, the COM will be somewhere on this line
- rotate object and repeat, where lines intersect is the COM
