Forces and their interactions Flashcards
What is a scalar quantity?
- only have a magnitude
What is a vector quantity?
- have a magnitude and and a direction
What is magnitude?
- a value for size
What does the arrow represent for vector quantities?
- size of arrow determines magnitude
- direction of arrow determines direction of the vector
What are some examples of scalar quantities?
- mass
- speed
- distance
- energy
- temperature
What are some examples of vector quantities?
- force
- velocity
- displacement
- acceleration
- momentum
What is a contact force?
- when objects are touching
What is a non-contact force?
- when objects are not touching or are separated
What are some examples of non contact forces?
- gravitational force
- magnetic force
- electromagnetic force
What are some examples of contact forces?
- air resistance
- normal contact force
- friction
- tension
What is a normal contact force?
- force at right angles to the surface
- eg. weight of book balanced by reaction force from the table
“normal” = at 90 degrees
How do you calculate weight?
w = m x g
weight = N
mass = kg
g = N/kg
How do you measure forces?
- using a newtonmeter
- calibrated spring balance (spring stretches fixed distance for each newton)
- weight of object considered to act at a single point known as centre of mass
What is the gravitational field strength on earth?
9.8 N/kg
What is a resultant force?
- single force that has same effects as many different forces acting together
What does a pair of different sized forces acting in opposite directions cause?
- a resultant force
- unbalanced forces causes resultant force
How do you calculate resultant forces?
- larger force - smaller force in opposite direction
- adding forces that act on the same side
What is weight?
a force acting on a mass due to gravity
What is mass?
the amount of matter that an object contains
