Ch.14 Physics Flashcards
Is work done on an object that moves in the opposite direction of the force acting on it?
No
What is the SI unit of work?
Joule
What is power?
The rate of doing work
How do you find power?
Dividing work over time
What is the SI unit if power?
Watt
How many joules of work is horsepower?
746J
What does a machine do?
Changes the direction,size,and distance of force making work easier
The work done by a machine is always less than the work done on a machine due to ________.
Friction
How do you find work input?
Input force•input distance
The number of times that a machine increases input force is the ________ ________.
Mechanical advantage
Which has less friction a bumpy rough ramp or a smooth surfaced ramp? Which requires more force to get up?
Smooth surfaced ramp; bumpy rough ramp
Does a rough loading ramp gave a greater MA than a smooth one?
No
What is IMA?
MA in the absence of friction
Is an inclined plane a machine?
Yes
Why is efficiency always less than 100%?
Friction is always present
Reducing friction ________ the efficiency of a machine.
Increases
What are the six simple machines?
Lever,pulley,wedge,screw,wheel and axel, and inclined plane
What is a screwdriver being used to open a paint can an example of?
Lever
What is the fixed point that a lever rotates around?
Fulcrum
What characteristics distinguish levers as first,second,or third class?
Fulcrum,input force,output force
What is a slanted surface along which a force moves an object to different elevation?
Inclined plane
Screws with threads closer together have a greater what?
IMA
What is a simple machine consisting of rope fitted into a grooved wheel?
Pulley
What is a compound machine?
A combination of two or more machines that operate together
What three things are compound machines?
Watch,car,and washing machine
What is work output over work input • 100?
Efficiency
What does dividing output work by output force find?
Output distance
What is the distance between the fulcrum and input force?
Input arm
What is a machine has IMA that increases when it’s thickness decreases relative to its length?
Wedge
What is exerting in a jack handle to lift a car an example of?
Input force
What is the distance between the output force and fulcrum?
Output arm
What is the distance input force acts through?
Input distance
In science, when work is done an ________ acts on an object in the direction the object moves.
Force
