Work, Power & Machines
How do machines make work easier?
(list 2 ways)
By changing the size or direction of the force
By increasing the distance over which the force acts
When you compare a movement to something that is not moving, the stationary object is your......
What is Frame of Reference?
What do you call a force that changes motion?
What is an unbalanced force?
Fluids may be either ___or ____
What is liquids or gases?
What do you call the ability to do work?
What is energy?
Why can't you get more work out of a machine than you put in?
There is always some sort of friction present
How does displacement differ from distance?
Displacement is a vector, so it includes distance and direction.
Newton's first law is known as "The Law of _____"
What is inertia?
Fluid pressure is determined by what two factors?
What is depth and type of fluid?
What are the two major classifications of energy
What are potential and kinetic?
What is the difference between actual mechanical advantage and ideal mechanical advantage?
Actual mechanical advantage compares forces, so friction is included.
Ideal mechanical advantage compares distances, so friction is ignored.
How do you calculate average speed?
By dividing the total distance by the total time.
What two factors determine the momentum an object has?
What is mass & velocity?
What does Pascal's Principle say that helps hydraulic devices work?
a change in pressure at any point is transmitted equally in all directions
Name at least 4 forms of energy
mechanical, thermal, chemical, electrical, electromagnetic, nuclear
What are the two types of pullies, and how do they differ?
Fixed pulleys change the direction of the force
Moveable pulleys multiply force
(Compound pulleys do a combination of the two)
If you create a distance-time graph, how can you tell the instantaneous speed of the vehicle?
The slope is the speed. (a horizontal line means there is a slope of zero, so the vehicle is not moving.)
Newton's law of universal gravity says every object is attracted to every other object in the universe based on .......
What is size and distance?
What does Achimede's Principle state about buoyancy?
The buoyant force on an object is equal to the weight of the displaced fluid.
What are some advantages of fossils fuels? Name 2
They are inexpensive, common and widely available
How do levers make work easier?
Answer for each class.
1st class- will change either force or distance depending on the location of the fulcrum
2nd class- multiplies force
3rd class- multiplies distance
If a car changes from 20 miles per hour to 55 miles per hour in 5 seconds, what is the car's acceleration?
(Be sure to include the appropriate unit)
What is 7 miles/hr/sec?
What are three universal forces?
What are electromagnetic, nuclear and gravity.
Briefly explain how an airplane wing works using Bernoulli's Principle.
Air moves faster over the wing creating low pressure, so the air under the wing tries to go from high pressure to low pressure creating lift.
Describe at least three energy conversions that would take place when cooking dinner
Chemical energy from food powers muscles to do mechanical energy to cut up food. Electricity from house changes to thermal to cook food. Chemical changes take place in cooked food.