P8- Forces in balance Flashcards
Contact force
The objects are physically touching
Non-contact force
The objects are physically separated
4 contact forces
Air resistance, normal contact force, friction, upthrust
3 non-contact forces
Electrostatic, magnetic, gravitational
Newton’s 3rd law
Two objects interacting will have an equal and opposite force on each other
Resultant force
Overall motion of the object, depending on the size and direction
Newton’s 1st law
An object will remain at rest or in uniform motion unless an external force acts upon it
Inertia
The tendency of objects to continue in their state of rest or in uniform motion
Distance
How far an object moves, doesn’t involve direction
Displacement
The change in position, a straight line from start to finish, with direction
Vector def?
Quantity that has magnitude and a direction
Scalar def?
Quantity that has magnitude but no direction
5 vector quantities
Displacement, velocity, acceleration, force, weight
7 scalar quantities
Temperature, mass, speed, energy, time, density, distance
Moment
The turning effect of a force, in a clockwise /anticlockwise direction
Lever
Act as a force multiplier so they reduce the force needed for a task
2 ways to increase the moment
-Increase distance from the object
-Increase force on the object
Load?
Effort?
Pivot?
Weight of object
Force applied to object
Point object turns about
Levers in an arrangement of
effort-pivot-load
Seesaw, crowbar, scissors
Levers in an arrangement of
pivot-load-effort
Wheelbarrow, nutcracker
Levers in an arrangement of
pivot-effort-load
Tweezers, tongs
Gears
Wheels with toothed edges that rotate around an axle
What do gears do
Allow for motion to be translated from one point to another
Increase or decrease the turning effect and speed
How to draw a parallelogram of forces
Rotate diagram so it’s horizontal to graph line, must be to scale
Draw the parallelogram
Measure resultant vector with ruler, angle w protractor
Speed
A measure of how fast an object is moving
Magnitude
The size of a quantity
Free-body force diagram
Forces acting on an object with no other objects or forces shown
Low gear
Size of gear wheel?
Speed?
Turning effect?
Small gear wheel drives large gear wheel
Gives low speed
High turning effect
High gear
Size of gear wheel?
Speed?
Turning effect?
Large gear wheel drives small gear wheel
Gives high speed
Low turning effect
What is the centre of mass of an object
The point where the mass is thought to be concentrated
What happens to the centre of mass of a suspended object?
It will come to rest with its centre of mass directly underneath the point of suspension
What are the moments when an object is in equilibrium
The total clockwise moment is equal to the total anti-clockwise moment
