Forces Flashcards
What is a scalar and vector quantity?
A scalar only has magnitude
A vector has magnitude and direction. Force is a vector quantity
What is a contact force and give examples?
objects are actually touching. E.G friction,tension,air resistence,upthrust
What is a non contact force and give examples?
Objects are not touching. E.G gravitonal force,electrostatic force ,magnetic force
What is gravity?
force of attraction between all mases
Mass is the amount of matter it contains and is constant
Weight is the force acting on an object due to gravity
Weight= mass x gravitational field strength (W=mg)
What is resultant force?
More then one force is acting on an object and they can be replaced with a single force which has the same effect
Force = Mass x Acceleration
F=ma
How is work done?
when a force causes an object to move ,work is done on the object
when work is done, energy transfers takes place within the system.
What is the difference between elastically/inelastically deformed?
elastically deformed=object returns to it original shape after the force is removed.
Inelastically deformed=objects does NOT return to its original shape
What happens once the limit of proportionality has been exceeded\?
Once the limit of proportionality has been exceeded doubling the force will no longer double the extension the relationship will become non-linear and curved
Force= spring constant x extension
F=ke
What happens to the particles in a fluid?
fluid is either fluid or gas
When particles move around in a container they collide and these collisions create a force to the surface.
What happens if there is a low atmospheric pressure?
greater the altitude ,the less dense the atmosphere lower the atmospheric pressure
What does pressure at a particular point in a column of liquid depend on?
height of the column above the point
density of liquid
Describe upthrust
the bottom surface has a higher pressure and creates a resultant force upwards
The upwards force exerted by a fluid on a submerged object is called up thrust
What is Distance?
Scalar quantity
how far an object moves
it does not take into account the direction
What is displacement?
Vector quantity
has magnitude this describes how far the object has travelled from the origin
it also has direction
What is speed?
measurement of how fast an object travels
scalar quantity
What is velcoity?
Vector quantity
when travelling in a straight line an object with constant speed also has constant velocity
What is a Distance-time graph used for?
used to represent the motion of an object travelling in a straight line
If an object accelerates the line will be a curve
What is velocity time graph used for?
used to find the acceleration of an object
How does an object accelerate when it falls through a fluid?
when an object falls through a fluid
objects accelerate due to the force of gravity
as it speeds up the resistive force increase
Do all object have momentum?
all moving objects have momentum but if it is not moving the momentum is 0
What is conservation of momentum?
In a closed system the total momentum before an event is equal to the total momentum after the event
conservation of momentum example
two cars travel at the same direction along a road.Car A collides with the back of car Calculate the velocity
of the car after the collision
momentum before collision-momentum A + momentum B
(mass A x velocity a) + (mass B x velocity of B)
(1200 x 20)+(1000 x 9)
24000 + 9000=33000kg m/s
momentum after collision=33,000kg m/s
momentum after collision = (mass A + mass B) x ( new velocity combined)
(1200 + 1000)=2200
33000/2200=15m/s
centre of mass
The single point through which the weight of the object can be said to act.
What do vector diagram show?
used to show the overall effect when more then one force acts on an object
OR can be used to show when a force is acting in a diagonal direction
How do you draw a vector diagram?
forces are added together to find a single resultant force including both magnitude and direction
vectors are added heat to tail and arrows are drawn
How do you draw a diagonal vector diagram?
diagonal line (FR)can be broken down to F1 and F2
F1 is the same length of FR in the horizontal direction
F2 is the same length of FR in the vertical direction
Give an example of work done?
E.G work done to overcome friction causes an increase in heat energy.
Work done= Force x distance
W=fs
1 joule=1 Newton Metre
Is extension directly proportional?
Extension of an elastic object is directly proportional to the applied force
What happens if the spring constant is high?
higher spring constant, stiffer the string
amount of work done and energy store is equal
SPRINGS DO NOT GO PAST THE LIMIT OF PORPORTIONALITY.
What happens of the pressure acts on a large area?
If the pressure act on a bigger area it will produce a larger force
When is there less air above the surface?
At a high altitude there is less air above a surface than at lower altitudes so there is a smaller weight acting on the surface
What does it mean if the column is high and the liquid is dense?
greater the pressure
greater the weight above the point
greater the force on the surface at that point
In terms of upthrust what happens when an object is less dense that the liquid?
*displaces volume of liquid greater than its own weight so it will rise to the surface
*will float with some of the object remaining below
the surface
How does an object sink or float?
If an object has a low density more of the object will remain above the surface
An object denser then its surrounding can not displace enough liquid to equal its weight so it will sink
When does an object sink or float?
An object floats when its weight is equal to upthrust and sinks when the weight is greater then upthrust
What factors affects speed?
Factors like age,fitness,distance affects the person who is walking,running,cycling
What happens if an object does not travel in a straight lien?
*the speed will be constant but the velocity will change as the direction changes
What happens if an object is moving in a circle?
- the direction is constantly changing so it constantly changing velocity
- it is accelerating even if it travelling at a constant speed
What happens when resultant force reaches 0 in terminal velocity?
resultant force reaches zero when the resistive forces balance the force of gravity. At this point the object will fall at a steady speed and its called terminal velocity
