P8 - Forces in Balance Flashcards
Contact Forces
- Objects have to physically touch
- Friction, trying to stop a moving object
- Air Resistance, effect of air
- Up thrust, liquid pushing a object to the surface
- Tension, squeezing/stretching
Force
Push or Pull due when interacting with an object, measured in Newtons
Non-Contact Force
- Force without touching
- Gravity
- Electrostatic, attract/repel between charged objects
- Magnetism, attract/repel in a magnetic field
Newton’s Law
- When objects collide, they exert equal force on each other
Action Force
Force you exert
Reaction Force
Force going against you
Presentation of Force
Longer/Bigger arrows represent difference of forces
Resultant Force
Difference of 2 forces
Equilibrium
If 2 equal forces move in opposite direction, it creates an equilibrium
Vector
Object presented by magnitude and direction, using an arrow (size presents magnitude, end represent direction)
Scalars
Objects presented by magnitude only
Centre of Mass in Regular Object
Where all lines of symmetry intersect
Centre of Mass in Irregular Object
- Tie object to a string and place a Plumbline near it which shows the centre of mass
- Draw a straight line though the Plumbline and Shape to find the centre of mass
Scalar Quantities
- Distance, doesn’t give direction
Vector Quantity
- Displacement, change from original position
- Velocity, rate of object changing its’ position
- Acceleration, change of velocity overtime
Diagonal Vectors
Means that there’s a vertical and horizontal force acting on it
Determine Horizontal/Vertical Forces
- Draw a graph with a key (1cm = 10N)
- Draw the arrow with the angle given starting from the origin
- Measure the X and Y axis using a ruler and use the key to work out the forces
Moment
Turning effect of a force in an anti/clockwise direction
Calculating Moment
Force x Distance from Pivot
Pivot Law
The further away the pivot is, the lesser the force is required
