Ch. 14 Flashcards
A vertical force (does, does not) work on an object that is moving in a horizontal direction.
does not
What is the SI unit of work?
joule
What is rate of doing work?
Power
How do you calculate power?
work/time
What is the SI unit of power?
watt
__________ is equal to one horsepower.
746 watts
Describe what a machine is able to do.
makes work easier
The work done by a machine is always less than the work done on a machine. Why?
friction
What equation describes work input?
work input= input force x input distance
The number of times that a machine increases an input forces is the _________________ of the machine.
mechanical advantage
Greater input force is required to move an object along a ramp with a rough surface because a greater force is needed to overcome __________.
friction
True or false?
A loading ramp with a rough surface has a greater mechanical advantage than one with a smooth surface.
false
A machine’s ______________________ is the mechanical advantage in the absence of friction.
ideal mechanical advantage
Why is the efficiency of a machine always less than 100% ?
there is always friction present
Reducing friction __________ the efficiency of a machine.
increases
List the six types of machines.
lever, wheel and axle, inclined plane, wedge, screw, pulley
List an example of a lever.
Using a screw driver to pry the lid off a paint can
What is the fixed point that a lever rotates around?
fulcrum
What characteristics levers as first-class, second-class, or third-class?
The position of the lever; first- between input and output forces third-between fulcrum and output force \_\_ second-output force is between input force and fulcrum
In science, work is done when a ________ acts of an object in the direction the object moves.
force
The ideal mechanical advantage of an inclined plane is the _________________________ divided by________________.
distance along the incline plane,
its change in height
Screws with threads that are close together have a greater _______________________.
ideal mechanical advantage
What is a compound machine?
a combination of 2+ simple machines that operate together
What are some examples of compound machines?
car,
washing machine,
watch
What is the equation for efficiency?
work output
___________ x 100%
work input
What is one way to determine output distance?
divide output work by output force
Where is the input arm located?
an a lever, it is the distance between the fulcrum and the input force
What machine increases as its thickness decreases relative to its length?
wedge
Where is an input force exerted?
on a jack handle to lift a car
What is the distance between the output force and the fulcrum?
output arm
What SI unit is used to describe a lightbulb?
watt
A slanted surface along which a force moves an object to a different elevation is called what?
inclined plane
What is the equation for power?
Work/Time
