Ch 7
Power
_________ is known as the force or work done by an individual.
work input or input force
Machines make work_______to do
easier
___________ is the equation used to calculate efficiency
wo/wi x 100
If a group of workers can apply a force of 1000 Newtons to move a crate 20 meters, what amount of work will they have accomplished?
20,000 j
What do we call a force that opposes motion?
What is friction?
What is Mrs. Luna's dogs name
Tito
The SI unit of power
Watt
The force that is exerted by a machine
Output force or work output
A simple machine that consists of two disks or cylinders, each with a different radius
Wheel and axle
FREE POINTS
If 68 Joules of work were necessary to move a 20 kg crate, how far was the crate moved?
0.347 m
When a force applied to an object causes the object to move in the direction of the force, the object acquires:
energy
What color is Tito's natural fur?
White and brown
The product of force and distance
Work
If there is no__________________no work is done.
movement
If an object is moving, then it also have ________ energy.
Kinetic energy
List 3 different simple machines
Incline plane, wedge, lever, pulley system, wheel and axle, screw
A worker uses a pulley system to lift a box. The machine does 600 J of useful work output, but the worker puts in 750 J of work input. What is the efficiency of the machine?
80%
The measure of how effective a machine is in using energy to do work is called __________.
efficiency
What type of dog is Tito?
Jack Russel/ Chihuahua
The SI unit of work
Joule
Formula for calculating work
work=force X distance
In a pulley system the rope will have ____ when a force is exerted on it.
tension force
What is the equation for the gear ratio? And what does each variable represent?
to/ti = ni/no
How much time is needed to produce 720 Joules of work if 90 watts of power is used?
about 8 seconds
Which simple machines uses a fulcrum to help increase efficiency?
lever
What is Tito's favorite toy?
Tennis balls
The equation to calculate work done against gravity is ________.
w=mgh
Machines change the size of a ________needed, the direction of a force, or the distance over which a force acts.
force
A v-shaped object whose sides are two inclined planes sloped towards each other
What does the work-energy-theorem state?
If an object has kinetic energy, then it is doing work. OR if an object tis moving, then it must be exerting energy
If 360 Joules of work are needed to move a crate a distance of 4 meters, what is the mass of the crate?
about 9.18 KG
What is the name of Mrs. Luna's cat? (I have 2... name 1)
Taka or Nibbler
How old is Tito?
11
Is equal to about 746 watts
Horsepower
When using SI units in the work formula, force is in _________and distance is in ____________
newtons;meters
In a lever, the fixed point about which the simple machine rotates is known as the _________.
fulcrum
What prevents machines from being 100% efficient. List 2 reasons
Entropy- heat
Friction
Light/sound/ etc
A worker uses 700 N of force to pull a rope a distance of 2 meters that releases the anchor on a ship. The anchoring system then applies 2857 N of force to adjust the distance to 0.5 in order to reengage the system. Calculate the efficiency of this device.
102%
__________ is efficient because it distributes the force , requires less force to move the object but you need to apply the force over a greater distance
inclined plane
What is Tito's favorite snack
cheese? or chicken?