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something that can change the velocity of an object
alway acts in the opposite reaction as to retard relative motion
when two objects are in close contact
is a unti of force which is 4.45N=1lb
when an object is at equilibrium all forces acting on it are equal to zero
depends more on the pressure between two surfaces rather than velocity
when a solid mass passes thru a liquid, gas or air vicous drag will occur. Viscous drag will increase as speed increases.
- - aerodynamic shapes come in to play
- -properties of the fluid also come into play
weight is equal to MG; mass x gravity
when you applhy pressure on a solid object, that object will bend but also push back with a force equal to one exerted on it.
tension can be measured by cutting a rope and introducing a spring scale
buoyancy acts in an upward direction on anything submerged in a liquid or gas.
An object with a weight greater than the booyancy of the fluid it is in will sink.
forces exist only in pairs
there are six simple machines
- these are
- 1. lever
- 2. incline plane
- 3. pulley
- 4. wedge
- 5. wheel and axle
- 6. screw
work is the force applied over a distance
Output ratio to inout ratio of work produced by a machine
whenever a force moves something over a distance. W=FxD
Force required to move 1 kilogram one meter in one second.
1kg x m/s
Mecahnical Advantage Formula
MA = Fl/Fe = load/effort
the force that actually produces horizontal movement when a force is appled at an angle.
ME= Wout/Win = work put out / work put in
a Force with both magnitude and direction
- there are 3 types.
- class 1- fulcrum between effort and load; dolly
class 2- Fulcrum on one end, with load between; wheel barrow, nutcracker
class 3- Effort in the middle of load and fulcrum; fisherman, tongs
plane set at and angle
MA = lenght / height
- Woutput = load x height
- Win= Force x lenght of ramp
A double inclined plane that moves to exert a force along the lenght of its sides to push two objects apart
-knife, ax, chisel
Wheel and Axle
wheel and axle
can be thought of as an inclined plane with a wedge wrapped around a cylinder.
forces are applied perpendicular to the groove
the pulley uses the principle of applying force over a longer distance. It also uses tension in the rope or cable.
MA of Pulley
De = Dl x supporting strands
E = Load / number of strands
W = F x D
liquids are nearly incompressible.
MA = Al / Ae
Aii / Ai = Di / Dii
- Aii = diameter of larger circle
- Ai = smaller
- Di= Vertical distance of smaller
- Dii=Larger one
MA = # of teeth in load gear / # of teeth in effort gear
- 1 ft-lb/s = 550 hp
- 746 joules = 1 hp