# Forces:Topic 5

- Created by: Lahlah_8
- Created on: 24-11-18 12:05

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- Forces:Topic 5
- Force Basics: 5a
- Contact Forces
- Non-Contact Forces
- Contact
- When two objects have to be touching for the force to act
- Examples: Friction, Air Resistance, Tension in ropes, Normal contact forces.

- When two objects have to be touching for the force to act
- Non-Contact
- When two objects do not need to be touching order for the force to be acting
- Examples: Magnetic forces, Gravitational forces, Electrostatic forces.

- When two objects do not need to be touching order for the force to be acting

- Contact
- Vector
- A quantity with both Direction and Magnitude
- Examples: Force,Velocity, Displacement, Acceleration, Momentum

- A quantity with both Direction and Magnitude
- Scalar
- A Scalar quantity is one with Magnitude and no Direction
- Examples: Speed, Distance,Mass, Temperature, Time

- A Scalar quantity is one with Magnitude and no Direction

- Non-Contact Forces
- Weight
- Mass
- Gravity
- Makes all things accelerate towards ground.
- It gives everything weight.
- Effects:

- Amountof matter in an object

- Gravity
- The force acting on an object due to gravity.
- Measured with a Newtonmeter

- Mass
- Resultant Forces
- With a numberof forces acting at a single point, replace them with a single force
- Resolving Forces
- Balanced forces
- Tip to tail

- Balanced forces

- Work Done
- When a force moves an object throughdistance, energy is transferred and work Is done on the object.
- WORK DONE(J) = DISTANCE (M) X FORCE(N)
- Working against a frictional force

- WORK DONE(J) = DISTANCE (M) X FORCE(N)

- When a force moves an object throughdistance, energy is transferred and work Is done on the object.
- Gravity,Mass and Weight
- Weight
- Mass
- Gravity
- Makes all things accelerate towards ground.
- It gives everything weight.
- Effects:

- Amountof matter in an object

- Gravity
- The force acting on an object due to gravity.
- Measured with a Newtonmeter

- Mass
- WEIGHT (N) = MASS (KG) X GRAV. FIELD STRENGHT (N/KG)

- Weight

- Contact Forces
- Forces and Elasticity: 5b
- Elastic Objects
- Elastically deformed
- Can go back to original shape an length once force Is removed

- Inelastically deformed
- Cannot return to original length or shape after force is removed

- FORCE(N) = SPRING CONSTANT (N/M) X EXTENSION (M)
- Extension is DirectlyProportional to load of force applied

- Limit of Proportionality
- The limit to the amount of force you can apply to an object for the extension to keep increasing proportionally
- Force- extension graph = curves upwards
- Extension-force graph = Curves downwards

- The limit to the amount of force you can apply to an object for the extension to keep increasing proportionally

- Elastically deformed
- Investigating Springs
- ELASTIC POTENTIAL (J) = 1/2 X SPRING CONSTANT (N/M) X EXTENSION (M)2
- Equipment: Spring, clamp, fixed ruler, pointer,hanging mass, masses, weight stand
- Use W=mg
- Record at eye level and repeat experiment avoiding any human error (although Random error will occur)
- Force/ Extension graph = line with slight curve
- Changes y/ Changein x = F/E = K
- Calculating speed

- Elastic Objects
- Forces and Motion: 5c
- Accelertion
- How quickly the velocityis changing
- ACCELERATION(M/S2)= CHANGE IN VELOCITY(M/S) / TIME TAKEN(S)
- Uniform acceleration
- Uniform acceleration is constant acceleration
- FINAL VELOCITY 2 (M/S) - INITIAL VELOCITY (M/S) = 2 X ACCELERATION(M/S2) X DISTANCE (M)

- Distance-Time Graphs
- Motion of something travelling in a straight-line
- Steeper= faster
- levelling off = decreasing in speed

- curves represent acceleration

- Steeper= faster
- SPEED= DISTANCE / TIME
- GRADIENT = SPEED
- Calculating speed

- Motion of something travelling in a straight-line
- Terminal velocity
- Friction
- If an object has no force propelling it then friction will slow it down
- always acts in opositedirection
- you get friction between two surfaces or an object passingthrougha fluid

- Drag
- most resistive forces = air resistance or drag
- keep object streamlined to reduce any drag = flow over more easily
- Increasing top speed
- reducing drag = streamined
- Increasing power o engine = driving force increases and drag force becomes equal to it

- Friction
- Velocity-time graphs
- Shows objectsotion
- GRADIENT = CCERELATION
- curve= changing acceleration
- downhill = deceleration
- Distance traveled
- change in vertical / changes horizontal
- AREA = BASE X HEIGHT

- Newton'sFirst Law
- Newton'sSecond Law
- Newton'sThird Law
- when two objects interact, the forces they exert on each other are equal and opposite
- Equilibrium
- State which forces are equal and opposite

- RESULTANT FORCE(N) = MASS(KG) X ACCELERATION (M/S2)

- Newton'sThird Law
- if the resultant force on a stationary object is zero, the object remains stationary
- if resultant force on a moving object is zero, it will carry on at the same velocity
- if there is a non-zero resultant force on an object, its velocity will change(accelerate in the direction of force)

- Newton'sSecond Law
- Inertia
- INERTIAL MASS (KG) = RESULTANT FORCE(N) / ACCELERATION (M/S2)

- Distance, Displacement, Speed and velocity
- Displacement
- Displacement is the distance and direction in a straight-line from n objectsstartingto finish point.

- Distance
- Distance is how far an object has moved

- Speed
- How fast something is going, no regardsdirection

- Velocity
- How fast something is going and in what direction

- Everyday speeds
- Walking= 1.5m/s
- Running = 3m/s
- Cyling = 6m/s
- Car = 25m/s
- Train = 55m/s
- Plane = 250m/s

- Displacement
- Investigating Motion
- Equipment: trolley, hook with mass, masses, pulley and light gate connected to data logger

- Accelertion
- Car Safety and Momentum: 5d
- Stopping Distnace
- STOPPING DISTANCE = THINKING DISTANCE + BRAKING DISTANCE
- Thinking distance
- distance the vehicle travels during drivers reaction time
- Brakingdistance
- Stopping Distnace
- STOPPING DISTANCE = THINKING DISTANCE + BRAKING DISTANCE
- Thinking distance
- distance the vehicle travels during drivers reaction time
- Brakingdistance
- distance the vehicle travels after braking
- how fast, quality of brakes, tyres, road surface, good grip

- How fast, how quick

- Typical stopping distances
- 30mph = 9m Think + 14m Brake
- 50mph = 15m Think +38m Brake
- 70mph = 21m Think + 75m Brake

- distance the vehicle travels after braking
- how fast, quality of brakes, tyres, road surface, good grip

- Stopping Distnace
- How fast, how quick

- Typical stopping distances
- 30mph = 9m Think + 14m Brake
- 50mph = 15m Think +38m Brake
- 70mph = 21m Think + 75m Brake

- Reaction Time
- Ruler-drop test

- Braking
- Brakingrelies on frictiion from brakes and wheels
- Frictioncauses work to be done
- Estimate:
- Rearrange V2-U2 = 2as

- Energy Transfer
- Momentum
- MOMENTUM (KGM/S) = MASS(KG) X VELOCITY(M/S)
- Greatermass = greater velocity= more momentum
- Conservation of Momentum
- In a closed system the overall momentum is the same before as it is after

- Stopping Distnace

- Force Basics: 5a

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