P5 Forces Flashcards
Define displacement
Overall distance travelled in a certain direction
Define vector
Have both size and direction
Can be negative
Give examples of scalar quantities
Distance
Speed
Time
Mass
Define scalar
Has size but no direction
Can’t be negative
Give examples of vector quantities
Velocity
Acceleration
Force
Weight
Displacement
Momentum
Define acceleration
A change in an objects velocity
What is the upwards force acting on a vehicle on land?
Normal contact
What is the upwards force acting on a vehicle on water?
Upthrust
What is the upwards force acting on a vehicle in air?
Lift
What happens when the gravitational field strength is strong?
The weight is larger
What happens when the gravitational field strength is weak?
The weight is weaker
What is the equation that links weight, mass and gravitational field strength?
Weight = mass x gravitational field strength
(N) (Kg) (N/kg)
W = m x gfs
What type of force is thrust?
Contact
Engine provides forward driving force
What type of force is gravitational/ weight?
Non contact
Attraction on anything with mass
What type of force is reactionary force?
Contact
An equal and opposite reaction force
What type of force is friction?
Contact
Force that opposes motion
What type of force is air resistance?
Contact
Air particles colliding with a moving object
What type of force is tension?
Contact
Force in a stretched or compressed object
What type of force is elasticity?
Contact
Restoring elastic force if object is stretched or compressed
What type of force is electrostatic?
Non contact
Attraction or repulsion between electric charges
What type of force is magnetism?
Non contact
Attraction or repulsion between magnetic poles
Define contact force
The objects are physically touching
Define non contact forces
The objects are physically separated
What happens if the resultant forces equal zero?
The forces are balanced
What happens to the movement of the object if the resultant force = zero?
Either move at a constant speed if already moving
Or remain stationary
What happens if the resultant forces do not equal zero?
The forces are unbalanced
What happens to the movement of the object if the resultant forces does not equal zero?
Stationary it will accelerate
Moving and resultant force is in same direction it will accelerate
Moving and resultant force is in opposite direction it will decelerate
Define centre of mass
Point at which the weight of an object appears to act from
How do you work out the centre of mass with an unsymmetrical object?
Hang object from a plumb line
Draw plum line onto object
Repeat from different points on the object
Where the lines intersect is the centre of mass
What equation links force, mass and acceleration?
Force = mass x acceleration
F = m x a
(N) (Kg) (m/s^2)
Define precise data
Gives similar results if repeated
Give equation that links acceleration, final velocity, initial velocity and time taken?
Acceleration = final velocity - initial velocity
Time taken
Define accurate data
How close your data is to the true value
How can accurate data be improved?
Repeating measurements
Calculating a mean
Drawing a line of best fit
(The closer your points are to your line of best fit the more accurate your results)
Define random errors
Errors made by carrying out the measuring
What do random errors affect.
Precision
What are some examples of random errors?
Reading the instrument incorrectly
Timing incorrectly
Define systematic errors
Caused by faulty equipment that doesn’t reset to zero properly
What does systematic errors affect?
Accuracy
A larger resultant force leads to
A larger acceleration
A larger mass leads to
A smaller acceleration
Define terminal velocity
Maximum velocity that a freely falling object will eventually reach
What is the equation that links weight, mass and gravitational field strength
W = m x g
What is stopping distance?
Stopping distance is the distance an object travels while attempting to stop
What is the equation linking thinking distance, braking distance and stopping distance?
Stopping distance = braking distance + thinking distance
What are the factors that affect thinking distance?
Distraction
Drugs
Alcohol
Eye sight
Tiredness
Age
What are the factors that affect braking distance?
Condition of brakes
Wet/ icy roads
Condition of tyres
Condition of road
What is the method for hooke’s law?
Measure the length of the original spring without weights attached
Add more weight to the spring
Wait for the spring to stop moving before measuring
Calculate total extension using
