chapter 14 study cards
how are the level and wheel axle related to each other?
A lever and a wheel and axle are similar because they are both simple machines that help make our lives easier and they both have a fulcrum which is the point on the machine that turns.
what does compound machine mean?
A machine consisting of two or more simple machines operating together, as a wheelbarrow consisting of a lever, axle, and wheel.
how does doing work at a faster rate affect the power required?
Doing work at a faster rate requires more power because the output has increased.
how is a machine able to increase a force ?
Energy = Force x distance travelled = work done (units=Joules)
what class or classes of lever always have a mechanical advantages ?
The class 2 lever has the fulcrum at one end, the force at the other end, and the load in the middle. A common example is the wheelbarrow, where the wheel is the fulcrum, the load rests within the box, and the force is the lift supplied by the user.
what is input force?
The effort force is the force applied to a machine. Work input is the work done on a machine.
what does input distance mean?
The effort force is the force applied to a machine. Work input is the work done on a machine. The work input of a machine is equal to the effort force times the distance over which the effort force is exerted.
what does output force mean?
The purpose of a machine is to create a mechanical advantage that will facilitate your ability to move an object against resistive forces.
when does a force do work?
There are many important examples of forces which do no work because they act perpendicular to the motion.
what is first, second, and third class lever?
This allows the identification of three classes oflevers by the relative locations of the fulcrum, the resistance and the effort: Class 1: Fulcrum in the middle: the effort is applied on one side of the fulcrum and the resistance (or load) on the other side, for example, a seesaw, a crowbar or a pair of scissors.
how are work and power related?
Work done is a measure of the energy transferred when a force moves a load, power is the rate of energy transfer.
why does work depend on direction?
Work is equal to Force x Displacement so displacement and force are the only factors involved in work.
what conditions must exist in order for a force to do work on an object?
a machine .
what does lever mean?
a rigid bar resting on a pivot, used to help move a heavy or firmly fixed load with one end when pressure is applied to the other.
what does screw mean?
a short, slender, sharp-pointed metal pin with a raised helical thread running around it and a slotted head,
what does wheel and axle mean?
a simple lifting machine consisting of a rope that unwinds from a wheel onto a cylindrical drum or shaft joined to the wheel to provide mechanical advantage.
what does pulley mean?
a wheel with a grooved rim around which a cord passes. It acts to change the direction of a force applied to the cord and is chiefly used (typically in combination) to raise heavy weights.
what is work?
activity involving mental or physical effort done in order to achieve a purpose or result.
what does machine mean?
an apparatus using or applying mechanical power and having several parts, each with a definite function and together performing a particular task.
How much work is done when a vertical force acts on an object moving horizontally?
any force that doesn't act in the direction of motion doesn't do work.
how do machines change direction?
by doing something different.
what does wedge mean?
force into a narrow space.
what is increasing distance?
growing larger, or greater.
who's James Watt and Horsepower?
he defined horsepower .
what is ideal mechanical average?
measure of the force amplification achieved by using a tool.
what does inclined plane mean?
plane inclined at an angle to the horizontal
how do you calculate power?
power= work/time.
what formula relates work and power?
power=work/time
what is power?
the ability to do something or act in a particular way, especially as a faculty or quality.
how are work input and work output related for a machine?
the amount of work put in is how it will come out.
what does output arm mean?
the outcome of the things people put into machines.
what does fulcrum mean?
the point on which a lever rests or is supported and on which it pivots.
what does mechanical advantage?
the ratio of the force produced by a machine to the force applied to it, used in assessing the performance of a machine.
what is efficiency?
the ratio of the useful work performed by a machine or in a process to the total energy expended or heat taken in.
what does input arm mean?
the things you put into the machine
what does work output mean?
the work done by a simple machine, compound machine, or any type of engine model.
how do machines make things easier?
things can be quicker and the machine does it for you.
how does changing the input arm affect the mechanical advantage?
transferring a force from one place to another, changing the direction of a force, increasing the magnitude of a force, increasing the distance or speed of a force.
what is work input?
which for simple machines is always less than the energy input, even though the forces may be drastically different.
what are the work formula(s)?
work=force X distance