Work, Energy, & Power: Exam
Show your work.  Show your units.  Give complete answers.  Get the correct answers.

In what way does a man holding a block of wood over his head not qualify as work (in the scientific context)?
 
 

On page 169, the equation given for net work includes the “cos q.” Why can you use only the cosine and not the sine?
 
 
 

If I pull the 10kg overhead projector by its cord for 5 meters at an angle of 15° from the horizontal, how much work will I have done on it pulled it if I accelerated it to 2 m/s2?
 
 
 

What is the kinetic energy of a 4 g pebble thrown with a velocity of 10 m/s?
 
 
 

How much more energy would that same pebble have if it was throw twice as fast?
 
 

Name something with a lot of kinetic energy primarily because of its mass.
 
 

Name something with a lot of kinetic energy primarily because of its velocity.
 
 

Give an example in which gravitational potential energy is converted to kinetic energy.
 
 

Give an example in which kinetic energy is converted to gravitational potential energy.
 
 
 

Give two ways in which you could maximize the gravitational potential energy in a wrecking ball
 
 
 
 

Give two examples of materials/objects/inventions/etc. with spring constants greater than that of a mattress spring.  (Be specific!)
 
 

What is the spring constant of a spring that has 400 J of elastic potential energy when it is compressed from 1.6 m to 1.2 m?
 
 

Why is it necessary to ignore friction when discussing the conservation of mechanical energy?
 
 

If a diver climbs to the top for a high dive and jumps off…
Where is his potential energy greatest?
 
 

Where is his kinetic energy greatest?
 
 

Where has work been performed (and by what)?
 
 
 

Explain the concept of power by using the words “energy,” “time,” and “power.”
 
 
 

If 25 W of power were applied, how much mass could be accelerated at a rate of 10 m/s2 over 100 meters for 0.5 seconds?
 
 
 
 
 


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