P8 - Forces And Ballance✔️ Flashcards
what is magnitude?
size of a quantity
what are scalars?
physical quantities that have size/magnitude but no direction
what are vectors?
physical quantities that have size/magnitude and direction
examples of scalar quantities?
distance, volume, density, mass, time, energy
example of vector quantities?
force, velocity, displacement and acceleration
equation for speed?
speed = distance/time
equation for velocity?
velocity = displacement/time
equation for force?
force = mass x acceleration
why is acceleration a vector quantity?
acceleration is a change in velocity therefore having direction and therefore a vector making it a vector quantity.
what do arrows show?
the direction of the vector quantity and the length represents the magnitude of the vector quantity.
what is force?
a force is a push or pull that acts on an object. Force is measured in Newtons(N)
what are example of contact forces?
friction, air resistance ,stretching(tension)
what are example of non-contact forces?
magnetic force , gravitational forces , electrostatic force
Newtons third law states …?
when two objects interact with each other they exert equal and opposite forces on each other. Example, if a person pushes a wall with a force of 50N the wall exerts and equal and opposite force back of 50N
Newtons first law states ….?
in order to make an object move from rest the forces must be unequal.
what is friction?
friction is the force exerted by a surface against an object when it moves across it.
equation for calculating the size of a moment
moment(Nm) = Force(N) x distance(m)
what is a moment?
a moment is a turning force, the turning effect of a force is called the moment of the force.
what are pulley and gears?
pulleys and gears are both simple machines commonly used to transmit rotational forces whilst also increasing or decreasing this rotation force(turning effect)
what is Centre of mass?
the mass of an object may be considered to act at a single point referred to as the objects ‘Centre of mass’.
what is resultant force?
is the force that is produced in a certain direction due to a combination of forces if the resultant force is zero the object will remain stationary if the resultant force is not zero the object will accelerate in the direction of the resultant force.
Newtons first law of motion states ….?
If the resultant force acting on a stationary object is zero then the object will remain stationary if the resultant force acting on a moving object is zero then object will continue moving in the same direction at the same speed.
What is displacment?
Displacement is the distance moved in a straight line, in a given direction, from the starting point
What happens when a car moves forward?Explain in terms of friction and forces?
Driving force on a car is the force that makes it move - this force pushes the car forward because their is friction between the ground an the tyre of each drive wheel
What are the resultant forces on a plane taking off?
The thrust force of its engine is greater than the force of air resistance(drag) on it - the resultant force on the plane is the difference between thrust and air resistance and is therefore greater than 0
Why does a car stop when the breaks are pressed explain in terms of resultant forces?
When breaks are applied the braking force is greater than the force from the engine - the resultant force if the difference between the braking force and the engine force
Example of a lever?
Crowbar is a lever that can be used t o raise one edge on a heavy object
What is the load when using a lever?
The load is the weight of the object
What is the effort when using a lever?
Effort is the force the person applies to the lever
Why is using a crowbar to lift a heavier object an exmaple of a force multiplier?
Because the effort moves a much bigger load
What does a low gear give?
Low gear = low speed and high turning effect
What does a high gear give?
High gear = high speed and low turning effect
What does it mean if a lever is used as a force multiplier?
It exerts a greater force than the force applied to the lever by the pivot
What happens to a small gear wheel when a low gear is used?
-Small gear wheel driven by engine shaft used to turn a large wheel on the output shaft
-turning effect of the output shaft is greater than the turning effect of the engine shaft
What happens to a large gear wheel when a high gear is used?
-Large wheel driven by engine shaft used to turn small gear wheel
-Turining effect of the output shaft is greater than the turning effect of the engine shaft
What is the centre of a mass of an object?
The centre of mass of an object is the point at which its mass can be thought as being concentrated
Principle of moments?
Sum of all clockwise moments about any point = sum of all the clockwise moments about that point
Equation for principal of moments?
W1 D1 = W2 D2
W=weight
D=distance
What is the parallelogram of focres?
Is a scale diagram of two vector forces - and is ued to find the resultant forces of two fores
What are the two conditions for and object to be in equalibrium?
-resultant forces of an obect are equal
-forces aacting on the object have no overall turning effect
What does it mean to resolve a force?
Means finding perpendicualr components that have a resultant force that is equal to the force
Is a bigger or lower turnig force exerted on the wheels with a low gear?
Bigger turning effect is exerted on the wheels