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Work Power GPE KE Misc. Energy Calculations 100 100 100 100 100 100 200 200 200 200 200 200 300 300 300 300 300 300 400 400 400 400 400 400 500 500 500 500 500 500

What is the unit of measurement for work?

Joules

Define ‘work’ Work 200

When a force causes an object to move in the direction of the force

Give an example of work being done.

Answers will vary- must include something moving in direction of applied force

A waiter is carrying a tray of dishes that weighs 10 N A waiter is carrying a tray of dishes that weighs 10 N. He walks the tray to a table 5 m away. How much work does he do on the tray? Work 400

0 J

Work 500 Could a 225 N force and a 75N force both do 225J of work? Explain.

Yes. 225N x 1m = 75N x 3m= 225J

What is the unit of measurement for Power?

Watts

Define Power. Power 200

Rate at which work is done… etc.

What must you know in order to calculate power? What is the formula?

P = work/time

What is the relationship between power and time?

As time decreases, power increases As time increases, power decreases

Jim has a power output of 625W after running up a set of stairs in 10s Jim has a power output of 625W after running up a set of stairs in 10s. How much work did he do? Power 500

W= P x t 6250J

What factors increase GPE

More mass, greater height

At what point on an incline plane would a ball have the most GPE- why?

Top, greatest height, most ‘potential’

Which statement best explains the change in the skier’s potential energy? a. The skier loses potential energy as she is lifted up the slope and loses potential energy as she skies down the slope. b. The skier gains potential energy as she is lifted up the slope and maintains the same potential energy as she skis down the slope. c. The skier gains potential energy as she is lifted up the slope and loses potential energy as she skis down the slope. d. The skier loses potential energy as she is lifted up the slope and gains potential energy as she skis down the slope. GPE 300

c. The skier gains potential energy as she is lifted up the slope and loses potential energy as she skis down the slope.

GPE 400 At what point does the pendulum have the greatest and least amounts of GPE? A B C

A= greatest, c= least

A diver has a 3400J of GPE after stepping up onto a diving platform that is 6.0m above the water. What is the diver’s mass in kg? GPE 500

m= GPE/ gh 3400/ 9.81 x 6 57.76 kg

KE 100 Define KE?

Energy of a moving object due to motion

KE 200 At what point is the pendulum moving the fastest? When is the KE the greatest? C B A

A

DAILY DOUBLE KE 300

A student plans to collect data needed to calculate the kinetic energy of a thrown baseball. She plans to measure the distance from pitcher to catcher, the time it takes for the baseball to arrive in the catcher’s glove, the mass of the baseball, and the circumference of the baseball. Which of these measurements is not needed to calculate the kinetic energy a. Measuring the mass of the ball. b. Measuring the flight time of the ball. c. Measuring the circumference of the ball. d. Measuring the distance from pitcher to catcher. KE 300

c. Measuring the circumference of the ball.

Which graph shows the kinetic energy of the space shuttle during the first few minutes of flight? (Launch time = 0) KE 400 A B C D

C

A rock is dropped from a high cliff until it hits the ground below A rock is dropped from a high cliff until it hits the ground below. Which statement below best describes the relationship between the kinetic and gravitational potential energy of the rock? (Air resistance can be ignored.) A. The gravitational potential energy the rock has at the top will be completely transformed into kinetic energy at the bottom. B. The gravitational potential and kinetic energies of the rock remain constant the entire way down. C. The kinetic energy decreases as the rock falls while the gravitational potential energy increases. D. Gravitational potential energy is destroyed while kinetic energy is created through molecule interactions between the rock and the air around it as it falls. KE 500

A. The gravitational potential energy the rock has at the top will be completely transformed into kinetic energy at the bottom.

The law of conservation of energy states that energy cannot be ___ or ____. Misc. Energy 100

Created or destroyed

Energy systems that constantly have energy flowing into and out of them are considered ___? Misc. Energy 200

open

Misc. Energy 300 mechanical energy is equal to…

PE + KE

Misc. Energy 500 Name at least 3 types of potential energy other than gravitational

Elastic, electrical, chemical, magnetic, etc…

Misc. Energy 400 In the Law of Conservation of energy, it is stated that energy can not be created or destroyed… only transferred or transformed. What does it mean to transfer or transform energy?

Transfer: pass along Transform: change into something new

Formula for work Calculations 100

W= F x d

Formula for Power Calculations 200

P = W/t

Formula for GPE and numbers units used for all parts Calculations 300

GPE = mass (kg) x free fall acceleration (9.81 m/s2) x height (m)

Formula for KE and units used for all parts Calculations 400

KE = ½ x mass (kg) x (speed (m/s) 2)

Daily Double! Calculations 500

How do you isolate for speed in the KE equation? Calculations 500

Square root of 2KE/m (or explain steps…) Or square root of KE/.5m