P5 - Forces Flashcards
Vector quantities
They have a magnitude and a direction force velocity displacement acceleration momentum
Scalar quantities
They only have a magnitude and no direction speed distance mass temperature time
Force
A force is a push or a pull on an object that is caused by it interacting with something. They are either contact or non-contact forces
Contact forces
When two objects have to be touching friction air resistance tension in ropes normal contact force
Non-contact
When two objects don’t need to be touching
Magnetic force
gravitational force
electrostatic force
Why weight and mass are not the same
Mass is the amount of ‘stuff’ in an object.
Weight is the force acting on an object due to gravity.
Gravitational field strength varies with location.
Gravitational field strength on the moon and earth
Moon - 1.6 N/Kg
Earth - 9.8 N/Kg
Weight equation
Weight = Mass x Gravitational field strength
Work done equation
Work done = Force x Distance
Applying a force to an object
it can cause the object to stretch, compress or bend.An object has been elastically deformed if it can go back to its original shape and length after the force has been removed. An object is inelastically deformed if it doesn’t return to it’s original shape and length after the force has been removed.
Force equation
Force is directly proportional to the extension
F = ke
Elastic potential energy equation
E = 1/2ke^2
Difference between Distance and Displacement
Distance is how far the object has moved. It is a scalar quantity so it doesn’t involve direction.
Displacement is a vector quantity. It measures the distance and direction in a straight line from an object’s starting point to its finishing point.
Distance traveled equation
Distance traveled = speed x time
Acceleration
The change in velocity in a certain amount of time
A = Change in Velocity / Time
Uniform/constant acceleration
v^2 - u^2 = 2as
Newton’s first law
If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it’ll just carry on moving at the same velocity.
Newton’s second law
The larger the resultant force acting on the object, the more the object accelerates.
Resultant force = mass x acceleration
Newton’s third law
When two objects interact, the forces they exert on each other are equal and opposite
Stopping distance equation
Stopping distance = Thinking distance + Breaking distance
Thinking distance is affected by:
- your speed
- your reaction time
Breaking distance is affected by:
- Your speed
- The weather
- The condition of your tyres
- How good your breaks are
Momentum equation
Momentum = mass x velocity
