Forces & WEP Flashcards
Hooke’s law
States that the force is directly proportional to the extension in a material if its limit of proportionality is not exceeded
F=kx
(Note: F against x graph must pass through origin to be directly proportional)
Difference between springs connected in parallel and series
Parallel: k=k1+k2
Series: 1/k=1/k1 +1/k2
Center of gravity
Point at which the whole weight of a body may be thought to act
Moment
Turning effect of a force. Moment of a force is equal to the product of the force and the perpendicular distance of the line of action of the force from pivot O
Torque of couple
Product of one of the forces F and the perpendicular distance d between the lines of action of the forces
Principle of moments
States that if a body is in equilibrium, the sum of all the clockwise moments about any axis must equal the sum of all the anticlockwise moments about the same point
Conditions for static equilibrium
Either translational equilibrium: Resultant force=0
Or rotational equilibrium: Resultant torque=0
How to check if system is equilibrium
All forces intersect at a common point, and the directions of the forces are either clockwise or anticlockwise in a closed shape like triangle
Density
Mass per unit volume
Pressure
Force per unit area, where force is acting at right angles to the area
(p=F/A)
p=ro gh
Archimedes’ principle
States that when a body is totally or partially immersed in a fluid, the upthurst is equal to the weight of fluid displaced
Principle of flotation
States that for an object floating in equilibrium, the upthrust is equal to the weight of the object
Equations for pressure vs upthrust
Pressure(Pa) =ro gh
Upthrust(N)=V ro g
=ro gh x A
Work done
Product of a force and the displacement in the direction of the force
(Area under F-x graph)
What must remain constant when use W=p x deltaV
Pressure of the surroundings
