P8 - Forces in Action Flashcards
What is a vector quantity?
has magnitude & direction
What is a scalar quantity?
has magnitude - no direction
What are 3 examples of vector quantities?
- displcmnt
- velocity
- force
What are 5 examples of scalar quantities?
- speed
- distance
- mass
- energy
- time
Define force.
push or pull btwn objcts
What is Newton’s first law?
if resltnt force. = zero, then it will remain stationary or at a constant speed
What is Newton’s second law?
if resltnt doesn’t = zero, then velocity will change & amount it changes depends on mass
What is Newton’s third law?
every action has an equal & opposite reaction
Define distance.
how far an object moves
Name 6 contact forces.
- tension
- friction
- air resistance
- normal contact force
- drag
- upthrust
Name 3 non - contact forces.
- gravity
- magnetic
- electrostatic
Which of Newton’s Laws explains normal contact force?
3rd
Define centre of mass.
point which the weight of object can be considered to act
What are contact forces?
objects physclly touching
What are non - contact forces?
objects physclly seperated
If an object doesn’t have a resultant force of zero, what does this mean?
object = accelerating
If an object does have a resultant force of zero, what does this mean?
object = stationary or constant speed
What is meant by an elastic material?
mtrl that returns to its orignal shape & size when force removed
What is the rule regarding moments?
total clockwise moment = total anti clockwise moment
What is the turning effect of a force called?
moment
When we calculate moments, what must the distance be?
perpendicular from line of action
State the unit for a moment.
Nm
Why are levers and gears used?
↑ moment of force
What are 2 example of levers?
screw driver, door handle
