Define
▪machines are made of a combination of only _______ simple machines.
six
a simple machine that has a slanted surface; a ramp is an inclined plane.
▪Inclined plane –
the point at which the lever pivots
▪Fulcrum –
made of two circular pieces, a wheel, or a disc, attached to an axle, or shaft.
▪Wheel and axle –
MA = length of slope / height
formula for wedges,
a simple machine consisting of an inclined plane wrapped around a cylinder.
▪Screw –
a simple machine made of a rigid bar that pivots at a fixed point, has two basic parts, a stiff bar that rotates and a fulcrum.
▪Lever -
the resistance force slides between the fulcrum and the effort force.
Second class lever –
▪There are two types of pulleys
fixed and movable.
▪the closer together the threads sit along the screw, the longer the __________ over which the force of effort is exerted and the more the forces multiplied.
distance
machines change two things about work.
the distance over which you do work, and the force required to do work
▪a ramp increases the distance, which must do the work, but decreases the amount of
force that you need to exert.
the fulcrum is somewhere in the middle; the effort forces are applied on one side, and the resistance force on the other.
▪First class lever-
▪for compound machines to work efficiently, friction must be reduced as much as possible through
lubrication and other techniques
length of the effort arm from the fulcrum(De) / the length of the resistance arm from the fulcrum (Dr).
▪Mechanical Advantage of a lever
▪in a pulley system, with a mechanical advantage of two, the rope must be pulled__________ as far as in a system with the mechanical advantage of one.
twice
a simple machine, consisting of a rope or cable that turns around a wheel
▪Pulley –
when the effort force is between the fulcrum and the resistance force.
▪Third class lever –
arrangement of pulleys designed to move heavy objects. Utilizing three ropes it makes the mechanical advantage three.
▪Block and tackle-
MA= wheels diameter / axles diameter
Mechanical advantage for wheel and axles
▪the six basic machines are
the inclined plane, the lever, the pulley, the screw, the wedge, and the wheel and axle.
a combination of two or more simple machines that does work a simple machine alone cannot do
Compound machine –
How many lever classes are there, according to the relative position of the fulcrum, the effort force, and the resistance force.
levers are sorted into three classes,
two back-to-back incline planes that separate an object and push it apart
▪Wedge -
MA = head circumference / pitch of threads
Mechanical Advantage for screws