Unit 2 - Forces Flashcards
What two effects does a force have on a body?
change position
deform
What is weight?
the force of gravity acting on a body
What is mass?
the quantity of matter of which a body is composed
Does density remain constant?
yes
What happens to the volume of a body if the mass increases?
changes proportionately
What is gravity?
acceleration due to gravitational attraction of two bodies
What is a centre of mass?
the point in a body where its mass is assumed to act
What is centre of gravity?
the point in a body where gravity is assumed to act
in a body with both centre of mass and centre of gravity, where will they be in relation to eachother?
the same place
Which factors are the maximum friction force dependant on?
texture of the surfaces
force pushing them together
what is the equation for coefficient of friction?
(micro) = friction force/force acting normally to the surface
Does lubrication reduce rolling friction?
no - but it may reduce wear
What is the first condition of static equilibrium?
the sum of all forces acting on the body must = 0
What is momentum?
it is an expression of the bodies persistence to continue in its present state of motion
What is the moment of a force?
its tendency to produce a rotation about an axis
what is another name for moment?
torque
what are the units of torque?
N m
What does a high mechanical advantage mean?
that the effort force is lower than the resistance force
Why do muscles operate at a force disadvantage?
speed of movement
range of movement
How many classes of lever are there?
3
Describe a 1st class lever
the fulcrum is located between the effort and resistance forces
Give examples of 1st class levers
see-saw
scissors
crowbar
Describe a 2nd class lever
the resistance is located between the fulcrum and the effort
Give examples of a 2nd class lever
wheelbarrow
nutcracker
Describe a 3rd class lever
The effort force is located between the resistance and the fulcrum
Give examples of a 3rd class lever
tweezers
fishing rod
What is the equation for tangential linear velocity?
v=rw
What is the equation for tangential linear acceleration?
a - r x alpha
What are the two equation for radial linear acceleration?
aR = v2/r = rw2