Forces Flashcards
A value with magnitude only is a ________?
scalar
A value with magnitude and direction is a ____________?
vector
Distance an speed are examples of _________ quantities
scalar
Force, displacement and velocity are examples of __________ quantities
vector
What is a contact force?
A force between two object which are touching
What ia a non-contact force?
A force between objects which are separated by space.
Give two examples of contact forces
e.g. friction, air resistance
List three non-contact forces
gravitational, electrostatic, magnetic
Define weight
The force of gravity acting on an object’s mass
What device is used to measure weight?
A newtonmeter
What is the name of the single point at which an object’s mass appears to act?
centre of mass
The center of mas of an object is…
the single point at which the objects weight appears to act.
The single force which has the same effect as the combination of all the different forces acting on an object is the ______________ _______________.
resultant force
Work is done when an object is ….
… moved through a distance
Moving objects with mass are said to have __________?
momentum
State the law of conservation of momentum
In a closed system the total momentum before an event is equal to the total momentum after an event.
State the equation which links gravitaional field strength, mass and weight
W=mg
State the equation which links distance, force and work done
W=Fs
State the equation which links extension, force and spring constant
F=ke
State the equation which links distance, speed and time
s=vt
State the equation which links acceleration, change in velocity and time taken
a=Δv/t
State the equation which links acceleration, mass and resultant force
F = ma
State the equation which links mass, momentum and velocity
ρ = mv
What is the unit of weight?
Newtons (N)
What is the unit of mass?
kilograms (kg)
What is unit of gravitational field strength?
newtons per kilogram (N/kg)
What is the unit of work done?
Joules (J)
What is the unit of force?
Newtons (N)
What is the unit of distance?
meters (m)
What is the unit of the spring constant?
Newtons per meter (N/m)
What is the unit of the spring extension?
Metres (m)
What is the unit of speed or velocity?
metres per secons (m/s)
What are the units of acceleration?
metres per second squared (m/s2)
What are the units of momentum?
kilogram metres per second (kg m/s)
When a spring is stretched and can then return to its original length it is known as __________ _______________
elastic deformation or elastic behaviour
When a spring is stretched and its length is permanently altered it is known as ___________ ____________
Inelastic deformation or inelastic behaviour
The limit of proportionallity of a spring is…
the length a spring can be stretched to before it no longer returns to its original length
Sketch the Force (y) -Extension (x) curve for stretching a spring from no force to beyond its elastic limit.
teacher to draw on board…
The stopping distance of a vehicle is the sum of the …..
thinking and breaking distances
The distance a vehicle travels while the driver is reacting is the …
thinking distance
The distance a vehicle travels which the driver is breaking is the …
breaking distance
Reaction time is…
the time it takes a driver to react
A typical reaction time is …
0.2-0.9 s
Factors which influence reaction time are…
tiredness, drug, alcohol, distractions
Fctors which affect breaking distance are …
weather conditions, conditions of breaks and tyres
Both thinking and breaking distance are affected by which factor?
speed of vehicle
The greater the speed of a vehicle, the _________ the force required to stop the vehicle
greater
The distance and object moves and the direction in which it moves is known as the _________
displacement
The speed of an object in a particular derection is its ___________
velocity
The change of an objects speed in a given time is the _________
acceleration
Acceleration of falling objects close to the earth is ________
9.8 m/s2
When the force moving an object is balanced by frictional forces it is moving at its _____________ _____________
terminal velocity
On a distance time graph a straight line represents…
constant speed
On a distance time graph a upward curve represents…
acceleration
On a distance time graph a curved line becoming horizontal represents…
decelleration
On a distance time graph a horizontal line represents…
stationary
On a distance time graph the gradient is used to calculate the …
speed or velocity
On a velocity time graph an upwards straight line represents …
acceleration
On a velocity time graph a downwards straight line represents …
decelleration
On a velocity time graph a horizontal line represents …
constant speed
On a velocity time graph a horizontal line along the x-axis represents…
stationary object
On a velocity time graph, when the line falls below the x-axis it indicates that the object is …
moving backwards
Calcuating the gradient of a velocity time graph gives the …
acceleration
Calculating the area under a velocity time graph gives the …
distance travelled
A typical walking speed is …
1.5 m/s
A typical running speed is …
3 m/s
A typical cycling speed is …
6 m/s
Sound in air travels at …
330 m/s
State Newton’s First Law
The velocity of an object will only change if a resultant force is acting on the object.
If balanced forces act on a moving object it will …
continue to travel at a constant speed
If balanced forces act on a stationary object it will …
remain stationary
State Newton’s Second Law
Force = mass x acceleration (The acceleration of an object is proportional to the resultant force acting on the object, and inversley proportional to the mass of the object)
State Newton’s Third Law
Whenever two objects interact, the forces they exert on each other are equal and opposite
The tendency of objects to continue in their state of rest or of uniform motion is known as …
inertia
