forces Flashcards
what is a scalar quantity
. A quantity that only has a magnitude
.doesent have an direction
what is a vector quantity
.a quantity that has both magnitution , but also associated direction
how can a vector quantity be drawn and what does is show
. as an arrow
.the length of the arrow represents the magnitude ]
.the arrow points in the associated direction
what is a force
a push of pull acting on an object due to an interaction with another object
give 3 examples of contact forces
.friction
.air resistance ]
.tension
give 3 examples of non-contact forces
.gravitational forces
.electrostatic forces
.magnetic forces
is force a vector or scalar quantity
.vector it has magnitude and asscociated direction
give 3 examples of vector quantities
. velocity
.displacement
.force
give 3 examples of scalar quantities
. temperature
.time
.mass
.speed
.distance
.energy
what is weight
the force that acts on an object due to gravity and objects mass
what quantities does weight depend on
.the objects mass
.the gravitational field strength at the given position in the field
what peace of equiptment can be used to measure an objects weight
spring balance
newton meter
what is the name given to the single force that is equivalent to all the other forces acting on a given object
the resultant force
what does it mesn if a force is said to do work
the force cuauses an object to be displaced through a distance
what occurs when work is done against frictional forces
. a rise in temp of the object
.kinetic energy is converted to heat
work done equation
work done = force times distance
why does air resistance slow down a projectile
. the object does work against the air resistance
.kinetic energy is converted into heat , slowing down the object
explain the relationship between the force applied and the extension of an elastic object
the extension is directly proportional to the force applied , provided that the limit of proportionality is not exceeded
what is meant by a inelastic deformation
. the object doesent turn to its orignal shape when the force is removed
equations resulting force , spring constant , and extension
force= spring constant times exstension
what type of energy is stored in a spring when it is stretched
elastic potential energy
what can extension be replaced with in the equation for spring force
compression
does a distance quantity require a specific direction
no specific direction is required so it is an scalar quantity
if an object moves 3 meters to the left and then 3 meters back to its initial position. what is the objectc total displacement
. the object has zero displacement
.displacement is a vector quanitity so it also involves direction
.the object starts and ends at the same point
state a typical value for the speed of sound
330ms
what is the typical value for human walking speed
1.5ms
what is the typical value for human running speed
3ms
state the equation linking distance speed and time
distance= speed times time
how can a speed be calculated from a distance time graph
the speed is equal to the gradient of the graph
state the equation for the average accleration of an object
accelaration= change in velocity / time taken
what can be said about an resultant force acting on an object , when it is falling at terminal velocity
. the resultant force is zero
.when at a terminal velocity , the object is moving at a constant speed and so isnt accelarating
state newtons first law for a stationary object
if the resultant force on a stationary object is zero, the object will remain at rest
state newtons first law for a moving object
. if a resultant force on a moving object is 0 , the object will remain at constant velocity , same speed at same direction
what can be said about the braking forces and driving forces , when a car is travelling at constant velocity
. the braking forces are equal to the driving forces
if an object changes direction but remains at a constant speed , is there a resultant force
since there is a change in direction , there is a change in velocity and so there must be a resultant force
state the defining equation for newtons second law
resultant force= mass times accelaration
state newtons second law in words
. an objects acceleration, is directlly proportional to the resultant force acting on it and inversely proportional to its mass.
what is the symbol used to represent an approximate value
a squiqly line
state newtons third law
whenever two objects interact , the forces that they exert on eachother are always equal and opposite.
what is the stopping distance of a vehicle equal to
the sum of braking and thinking distance
for a given braking distance , if the vehicles speed is increased . what can be said about its stopping distance
the stopping distance is increased with an increase in speed.
give a typical range of value for human reaction times
0.2-0.9 seconds
give 3 factors which can affect a drivers reaction time
.tiredness
.drug
.alchahol
give 2 factors which may affect braking distance
. adverse road conditions
.poor tyre,brake conditions
desribe the energy transfers that take place when a car applies its breaks
. work is done by the friction force between the brakes and wheel
.kinetic energy of the wheel is converted to heat and is disspated to the surroundings through the brake discs
to stop a car in a given distance , if its velocity increased , what must happen to the braking force applied
the braking force must also be increased
state two consequences of a vehicle undergoing very large decelerations
. kinetic energy converted to heat is very high , causing breakes to overheat
.loss of control of the vehicle
