What is Work?
Mech. Advan. and Efficiency
Simple Machines
Machines in the Body
Mixed Bag!
100
What is units do we use to talk about work? a) Joules b) Newtons c) Pascals d) Meters
a) Joules
100
A _______ is a device with which you can do work in a way that is easier or more effective.
machine
100
Give an example of a wheel/axle.
A doorknob, steering wheel, etc...
100
What connects muscles to bones?
Tendons!
100
What is the formula for Force?
Force = mass x acceleration
200
What is the formula for Work?
Work = Force x distance ( w = Fd)
200
What is output force?
The force exerted by a machine.
200
What are the six kinds of simple machines?
Pulley, inclined plane, wedge, screw, lever, wheel & axle
200
An incisor is an example of which simple machine: a) wheel & axle b) wedge c) inclined plane d) pulley
b) wedge
200
How do you calculate the efficiency of a machine?
Output work divided by input work, all times 100.
300
In order for you to do work on an object, you must ______ as a result of your force.
move the object some distance (in the same direction as the force!)
300
Which is NOT one of the three ways machines make work easier: a) Multiplying force b) Multiplying force and distance c) Multiplying distance d) Changing direction
b) Multiplying force and distance
300
A ________ is a grooved wheel with a rope wrapped around it.
pulley
300
How many classes of levers are used by your body?
All three!
300
Whose Principle is this: "When a force is applied to a confined fluid, an increase in pressure is transmitted equally to all parts of the fluid." a) Bernoulli b) Archimedes c) Newton d) Pascal
d) Pascal
400
True/False: You can only do work *without* motion.
False - with motion.
400
True/False: The mechanical advantage is the number of times a force *exerted on a machine* is multiplied by the machine.
True.
400
How do you calculate the Ideal Mechanical Advantage of a lever?
Distance from fulcrum to input force DIVIDED BY distance from fulcrum to output force.
400
True/False: Your *ear* is an example of the human body's fulcrums.
False - any joint could be used in place of ear
400
What is acceleration?
The change in velocity in a given direction over time (m/s^2)
500
1 Joule = (what units?)
1 Newton x 1 meter
500
What is the difference between the Ideal Mechanical Advantage of a machine and the Actual Mechanical Advantage?
IMA is without friction, AMA is with friction.
500
How do you calculate the IMA of a compound machine?
Multiply the IMAs of all the simple machines that make it up.
500
When your biceps contract, what is the result?
Your arm bends.
500
True/False: The law of conservation of momentum states that... The total momentum of any group of objects *constantly changes* unless outside forces act on the objects.
False: remains the same (doesn't change)
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