P8 Flashcards
What is Displacement?
Distance in a given direction
What is a vector quantity?
Physical quantity which has magnitude and direction
What is a scalar quantity?
A quantity with only magnitude
How can a vector quantity be represented?
By an arrow in the direction of the vector, and of length in proportion to the magnitude.
What can forces do to an object?
Change its shape or change its motion or state of rest
What is the unit of force?
Newton
What is a contact force?
A force that acts on objects when the objects touch eachother
Describe the force that is created when 2 objects interact.
Equal and opposite
What is the resultant force of 2 objects acting on each other?
A single force that has the same effect as all the forces acting on an object.
What happens to an object if the resultant force of an object is 0?
The object stays at rest or maintains its speed
What happens to an object if its resultant force is greater than 0?
The speed or direction of the object will change.
What does a free body force diagram of an object show?
The forces acting on it
What is the moment of a force?
A measure of the turning effect of the force on an object
What is the equation for the moment of a force around a pivot?
moment(M)=force(F) X Perpendicular distance from the line of action of the force to the pivot(d)
What are the units for the moment equation?
Newton meters(Nm)= Newtons(N) X Meters(m)
What can be used to exert a force that is greater than the effort?
A lever
What does a lever act as?
A force multiplier
How are gears used?
To change the moment of a turning effect
What happens to increase the moment of a turning effect?
a small gear wheel needs to drive a larger gear wheel
What is the centre of mass of an object?
The point where it’s mass can be thought of as being concentrated.
What happens when an object is freely suspended?
It comes to rest with its centre of mass directly underneath the point of suspension
Where is the centre of mass of a symmetrical object?
Along the axis of symmetry
What does w1d1=?
w1d1=w2d2
If an object at rest doesn’t turn, what does the sun of the anti-clockwise moment at any point equal?
the sun of the clockwise moments about that point.
What happens to an object when a force acting in an object doesn’t pass through a fixed point?
The object can turn around that point
What determines whether the moment acts clockwise or anticlockwise?
The direction of the force and position of the fixed point
The parallelogram of forces is what?
Scale diagram of 2 force vectors
What is the parallelogram of forces used for?
to find the resultant of 2 forces that do not act along the same line
What does resolving a force mean?
Finding perpendicular components that have a resultant force that is equal to the force
How do u resolve a force in 2 perpendicular directions?
Draw a rectangle with adjacent sides along the 2 directions so that the diagonal represents the force vector.
