P8 Flashcards
what is displacement
distance without change in direction
what is a vector
a physical quantity with a direction
what is a scalar
a physical quantity that has a size but no direction
what are contact forces
when the two objects must touch in order to interact, the forces are contact forces
what is newton’s third law of motion
when 2 objects interact with each other, they exert equal and opposite forces on each other
whaqt happens in terms of friction when a car moves forwards
the force of the friction of the road on the tyre is in the forwards direction and the force of the friction of the tyre on the road is in the reverse direction
what is the resultant force
the single force that has the same effect as all the forces acting on the object
what happens when the resultant force is 0
the forces are balanced so the object stays at rest or at the same speed and direction
what happens when the resultant force is above 0
the speed or direction of the object will change
what is a free body force diagram
shows the forces acting on an object without and other objects or forces shown
how do you increase the turning effect/ moment of a force
increase the force or use a longer lever
what is the equation for moment
force x perpendicular distance from pivot
what are levers used for
they act as a force multiplier, increasing the line of action of the force you apply to exert a force that is greater than the effort or to make the object turn more easily
what happens when a low gear is chosen
low gear gives low speed and high turning effect as a small gear wheel driven by an engine shaft is used to turn a large gear wheel on the output shaft so the output shaft turns slower than the engine shaft
what happens when a high gear is chosen
high gear gives high speed and low turning effect so the large gear wheel driven by the engine shaft is used to drive the small gear wheel on the output shaft so the car can move at a higher speed
what is the centre of mass of an object
the point at which its mass can be thought to be concentrated
what is suspended equilibrium
when an object is freely suspended, it comes to rest with its centre of mass directly below the point of suspension
what is the principle of moments
sum of clockwise moments about any point = sum of anticlockwise moments around that point
what are the conditions for an object to be in equilibrium
resultant force = 0
forces acting on teh object have no overall turning effect
how do you resolve a force
finding perpendicular components that have a resultant force that is equal to the force
