Work and Simple Machines Flashcards
Is driving a car at a constant speed and direction work? Assume no wind resistance, friction, or other forces are acting on the car.
No. There is no acceleration.
No acceleration=no work
What is the SI unit for work?
Joule
Which is also the unit for Energy as well.
Is driving a car at a constant speed and direction work? Assume that there is friction and other forces acting on the car.
Yes. A force is needed to overcome the forces that would slow the car down.
Is lifting a paperclip work?
Yes you are applying a force against gravity.
How much work did you do if you moved an object 3 m with 2N of force?
6J
Work=force times distance
In which of the following ways does a machine make it easier for you to do a task.
Change the direction a force needs to be applied, Decrease the distance moved, Increase the distance moved, Decrease the force required, Increase the force required, Decrease the energy required to do the task, Decrease the work needed to do the task.
A machine could
Change the direction a force needs to be applied, Decrease the distance moved, Increase the distance moved, Decrease the force required (multiply force), Increase the force required
Total energy and work cannot be reduced no matter what you do.
What is the trade off for using a machine to decrease the force that is required to do a certain amount of work?
You will need to apply the decreased force over a greater distance to keep the amount of work the same.
Why is it impossible for a perpetual motion machine (one that will run forever without using extra energy) to exist?
No machine is 100% efficient due to friction and other forces that act on the machine.
Give an example of a wheel and axle as part of a complex machine.
Answers will vary.
How can you determine the Ideal mechanical advantage of a pulley?
Count the rope segments that hold up the load.
Is a stapler a compound machine? Explain why or why not.
Yes, because a stapler is made of more than one simple machine.
What is used whenever work is done?
Energy
Energy is the ability to do work. If work is done energy is transformed.
What is power equal to?
Work over time. Give you an indication of the ability of something to do a certain amount of work.
How many watts in 1 horsepower?
746 watts = 1 horsepower
What is the SI unit of Power?
Watt
