MODULE 3: FORCES AND MOTION Flashcards
stopping distance
THINKING + BRAKING distance
Center of mass
Point where external forces produce a straight line of motion with no rotation
Center of gravity
Point where entire weight of object appears to act
Experiment to find center of gravity
EQUIP: stand, paper, plumb line
EXPERIMENT: suspend paper freely using stand,
Use plumb line to draw a straight vertical line on the object
Rotate the object and do this again
Intersection = center of gravity
What is drag?
Resistive forces when a object moves through a fluid
What is a fluid?
Liquid or gas
What is drag proportional to
Velocity squared
What is terminal velocity
When drag is equal to weight, so Fres = 0.
What is the moment of a force?
Product of force applied and the perpendicular distance of the line of action from the pivot .
Moment equation
Moment = fx so newton meters
What is the principle of moments
Sum of anti-clockwise moments is equal to the sum of clockwise moments about the same point OR axis
Conditions for equilibrium
Fres is zero
Resultant Moment is zero
What is a couple
Two forces equal in magnitude but opposite in direction
What is the torque of a couple
Product of one of the forces (they are the same) and the perpendicular separation between them
How is torque and moment related
Torque is the same as total moment of the two forces about the midpoint between the forces
Density equation
ρ=mass / volume
How to measure density
Measure mass using weighing scale
Measure volume, for regular measure using callipers each edge. For irregular solids find displaced volume using displacement can
What is pressure
Normal force exerted on a surface. Pressure is force over cross sectional area
What is Archimedes principle
The upthrust exerted on a body immersed in a fluid (partially or fully) is equal to the weight of the fluid that the body displaces