Pounds English System Newtons SI (System International)
Slide 8
Force can be measured by spring balances or ____________.
Slide 9
Force can be measured by spring balances or scales
Slide 10
___________ forces equal and opposite. __________ forces one
side stronger. Gives a NET FORCE.
Slide 11
Balanced forces equal and opposite. Unbalanced forces one side
stronger. Gives a NET FORCE.
Slide 12
___________ - shows only magnitude (strength) Examples:
Slide 13
Scalars - shows only magnitude (strength) Examples:
Temperature, Elapsed time, pressure and mass.
Slide 14
__________ - shows both magnitude and direction. Examples:
Slide 15
Vectors - shows both magnitude and direction. Examples: Force,
displacement, velocity, acceleration and momentum.
Slide 16
Slide 17
Vector lines are drawn with an arrow. ___________ = magnitude
of vector (strength) ___________ = direction the force is
acting.
Slide 18
Vector lines are drawn with an arrow. Length of arrow =
magnitude of vector (strength) Direction of arrow = direction the
force is acting.
Slide 19
2 or more forces in the same direction you can add to get the
total force (net force). 2 or more forces in the opposite
direction, you subtract to get the net force.
Slide 20
If forces dont act along the same line you cannot add or
subtract. You have to graph and measure the resulting line (or use
trigonometry). You have 30 lbs pulling North and 40 lbs pulling
East. What is the resulting force?
Slide 21
1. Chose a scale (say 1 cm 10 lbs) 2. Graph the 2 forces at the
correct angle matching the head of one line to the tail of the
other line. 3. Draw the resultant line. Measure that line and use
your scale to determine its magnitude.
Slide 22
_________ is force in rotation mechanical systems. It is
measured in ___________ or __________ T=F x L
Slide 23
Torque is force in rotation mechanical systems. Measured in lb
ft or N m T = F x L
Slide 24
Torque = _____________ x _____________ ____________ is the
shortest distance from the rotation axis to the line of
action.
Slide 25
Torque = applied force x lever arm The lever arm is the
shortest distance from the rotation axis to the line of
action.
Slide 26
If the lever arm is 12 inches (1 foot) and you use 40 lbs of
force to turn it find the torque:
Slide 27
T = F x L 40 lbs x 1 ft = 40 lb ft
Slide 28
You need 80 Nm of torque to turn a bolt. You can apply 100
Newtons of force. How long of a wrench (lever arm) do you
need?
