Work
True or false: In physics pushing an object that does not move is NOT considered work.
True. There must be force and distance.
Check each other. Examples include levers, pulleys, ramps, etc.
True or false: A book up on a high shelf has potential energy.
True. The book has energy due to its position.
True or false: Energy can be destroyed.
False: The law of conservation of energy says that energy only changes form - it is not created or destroyed.
This date on the calendar has the longest night (period of darkness).
What is December 21?
This unit for work is the same unit that measures energy.
What is Joules (J)?
When using a simple machine, input work is _______________ output work.
a. Greater than
b. Less than
c. Equal to
c. Equal to
This has more potential energy:
a. A 0.5 kg apple 3 m up in a tree
b. A 70 kg person 3 m up on a ladder
What is the person on the ladder? (More mass)
This is the location on a ramp at which a skater would have entirely potential energy with no kinetic energy.
What is the top of the ramp?
This Jewish holiday is celebrated in December. It is marked by the lighting of 8 candles.
What is Hanukkah?
How much work is being done to raise a 2 kg pendulum 0.5 m?
What is 1 J?
W= f x d
The advantage of using a simple machine is that it does this to the amount of input force.
What is lowers the input force?
This has more potential energy:
a. A 2 kg shampoo bottle on a 1.5 m shelf
b. A 2 kg shampoo bottle on a 0.5 m shelf
a - The higher shelf
This is the location on a ramp where a skater would have entirely kinetic energy.
What is at the bottom of the ramp?
In the song, "Frosty the snowman," this is the object that makes frosty come to life.
What is an old silk hat?
Old MacDonald performed 800 J of work on his farm over a distance of 40 m. This is the amount of force he used.
What is 20 N?
W = f x d
The tradeoff/disadvantage of using a simple machine is that it does this to the input distance.
What is increases the input distance?
This is the amount of potential energy a 0.6 kg basketball has when it is 3 m in the air. (Remember g = 9.8 m/s/s)
What is 17.64 J?
What is 100 J?
(Half of energy is KE and half is PE here.)
This reindeer of Santa's shares a name with a famous symbol of Valentine's Day.
Who is Cupid?
In raising a 3,000 N piano with a pulley system, it is noted that for every 2 m of rope that is pulled, the piano raises 0.2 m. This is the amount of input work that would be needed to lift the piano 1 m.
What is 3,000 J?
(You figure out why - this style of question could be a level 4 question.)
When using a pulley, Homer used 2 N of force to pull a string 3 m. If the output force was 6 N, how high did the object raise?
What is 1 m?
Input f x d = Output f x d
This is the mass of a book that has 5 J of energy when it is on a 2 m shelf.
(g = 9.8 m/s/s)
What is 0.25 kg?
If a skater has 200 J of potential energy at the top of a 8 m ramp, this is how much kinetic energy he has when he is on his way down, 2 m from the ground.
What is 150 J?
(75% of energy is kinetic at this point.)
This holiday decoration is actually a parasitic plant.
What is mistletoe?