Vocab
Work & Power
Energy
Calculating Work, Power & Energy
Potpourri
100
the product of force and distance
What is work?
100

When does "zero" work occur?

When an object is at rest

100

Energy of motion

What is kinetic energy?

100

A 500 kg roller coaster is traveling 7 m/s at a height of 25 m.  Calculate mechanical energy.

134750 J

100

An apple falls from a tree. What kind of work is being done on the apple by gravity?

Positive

200

Energy stored in a compressed object.

What is elastic potential energy?

200

Work is positive when...

The force and displacement are in the same direction.

200
True or False:  Work is equal to a change in kinetic energy.

True

200

A 2.1 kg rock is being held at a height of 8.7 m.  Calculate it's kinetic energy just before hitting the ground.

179 J

200

Kyle is pushing his physics book away from him across the table. Is work being done?

Yes

300

Stored energy is known as

What is potential energy?

300

True or False: Running and walking up the stairs require the same amount of work

True

300
The sum of kinetic and potential energy.

What is mechanical energy?

300

A spring with a spring constant of 125 N/m is stretched to 1.7 m. Calculate its elastic potential energy if its rest position is 1.3 m.

10 J

300

A 1500 kg car is being pushed down a road at a speed of 1.4 m/s.  How much work must be done to increase the speed to 1.9 m/s

1237.5 J

400
rate of doing work
what is power?
400

(Assume masses are equal) AJ and CJ both lug their books up a flight of steps. AJ get up there in 1 minute while it takes CJ 1.5 minutes.

Who is more "powerful"?

AJ

400

An object contains 200J of GPE. What is one change you could make to this object or it's surroundings to increase its GPE? 

Increase it's mass

Increase it's height above the ground

Increase gravity (change to a planet with g greater than 9.8)

400
Erin is lifting a 7 kg bowling ball up from the 2nd floor to the third from over the railing a distance of 2.5 meters. What is the work done?
171.5 Joules
400

Peter is setting a box down on the floor.  Is positive or negative work being done?

negative work.

500

A unit of power which equals to one joule per second

The Watt?

500

Students do 75 Joules of work to push a table. How much energy was used by the students?

75 Joules

500

When energy in a system is "lost", it commonly transforms into heat. This indicates that what external force is present?

Friction/air resistance

500

Your family is moving to a new apartment. While lifting a box 1.5 m straight up to put it on a truck, you exert an upward force of 200 N for 1.0 s. How much power is requried to do this?

 300 W 

500

Steph is carrying her book across the room by balancing the book steady on her hand. Is work being done on the book?

No

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