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Work

Potential energy

Kinetic energy

Energy graphs

Conservation of energy

Mystery

Work Potential Energy Kinetic Energy Energy Graphs Energy Cons. Mystery 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

This is the unit for work.

What is Joule (J)?

Work is done when this happens.

What is when a force moves a distance?

This is the formula for work when a force is applied at an angle.

What is W = Fdcosθ?

A 5-kg textbook is held over a student’s head for 5 minutes A 5-kg textbook is held over a student’s head for 5 minutes. This is the work done.

What is zero?

As an apple falls from a tree, gravity does ______ work and air resistance does _______ work.

As an apple falls from a tree, gravity does positive work and air resistance does negative work.

The “x” in the spring potential energy equation represents this physically.

What is the distance the spring is stretched?

These are the names and formulas for the two types of stored energy.

What are… Elastic: ½kx2 Gravitational: mgh

A spring, with constant 200 N/m, is stretched 0. 1m A spring, with constant 200 N/m, is stretched 0.1m. This is the energy stored in the spring.

What is PE =1/2 kx2 = (0.5)(200N/m)(0.1)2 =1 Joule

A 5-kg weight is lifted 4 meters in the air A 5-kg weight is lifted 4 meters in the air. This is its potential energy.

What is ~200 J?

A spring, with constant 100 N/m, has 50 Joules of energy A spring, with constant 100 N/m, has 50 Joules of energy. What distance is it being stretched?

What is 1 meter?

Kinetic energy is the energy of _______.

What is motion?

(True/False) Kinetic energy can be negative.

What is false?

A 10kg car doubles its speed from 10m/s to 20 m/s A 10kg car doubles its speed from 10m/s to 20 m/s. Its KE changes by this factor.

What is quadruples?

A skydiver releases a parachute and falls at terminal velocity A skydiver releases a parachute and falls at terminal velocity. Her Kinetic energy Increases Decreases Remains the same Not enough information

What is “c” remains the same?

A 4-kg dog has a momentum of 40 kg m/s A 4-kg dog has a momentum of 40 kg m/s. This is the dog’s kinetic energy.

What is 200 J?

The kinetic energy is a maximum at this/these point(s).

What is point c?

Below is the kinetic energy graph of an object Below is the kinetic energy graph of an object. Draw its potential energy graph.

What is…

Daily Double!

Below is a potential energy graph Below is a potential energy graph. If total mechanical energy is conserved, this is the kinetic energy graph.

Draw the PE, KE, and tot. E graph

What is…

This is the KE graph

What is…

This is the total mechanical energy.

What is (all the PE) + (all the KE)?

A 1-kg apple has 100J of potential energy hanging in a tree A 1-kg apple has 100J of potential energy hanging in a tree. If it falls, it has this much kinetic energy just before it hits the ground.

What is 100 Joules?

An apple falls from a 5m tree An apple falls from a 5m tree. How fast is it moving just before it hits the ground?

What is 10m/s?

If a baseball is thrown straight up with a speed of 20 m/s, this is the maximum height it will reach.

What is 20 m?

A spring with spring constant 9. 0 N/m is compressed 0. 1 meters A spring with spring constant 9.0 N/m is compressed 0.1 meters. This is how fast a 1-kg ball will travel if it is pushed by the spring.

What is 0.3 m/s?

The units of velocity are this.

What are m/s?

A net force of 45 N is applied to a 5. 0-kg book bag A net force of 45 N is applied to a 5.0-kg book bag. This is the bag’s acceleration.

What is 9 m/s2?

A certain spring is stretched a distance of 1m A certain spring is stretched a distance of 1m. If its total force is 10N, what is the spring constant?

What is 10 N/m?

This is the weight of a 10-kg box on earth.

What is 98.1 N (or ~100N)?

Daily Double!

Which pair of vectors, A & B, would combine to produce the resultant vector R?

What is…

Final Jeopardy

Energy Conservation

A 5 kg mass compressed against a spring has 105 Joules of stored energy. As it moves from A to C it loses 5 Joules of energy. How high does it roll?

What is… ~2 meters high?