MOTIVATION TIME!

Are you ready, kids?

QUOTATIONS: How do you relate in our daily lives? Explain.

“The energy of the mind is the essence of life.”

- Aristotle

“Knowledge is power.”

- Francis Bacon

“The best preparation for good work tomorrow is to do good today.”

- Elbert Hubbard

How it is relate to our lesson? Did it find difficult to analyze?

WORK, ENERGY and POWER

OBJECTIVES

A. Describe and differentiate work, energy and power.

B. Differentiate potential and kinetic energy.

C. State the law of conservation of energy and work-energy theorem.

D. Solve problems involving work, energy and power.

WORK

Work is a scalar quantity with refers to an activity involving a force (F) and movement in the direction (d) of the force.

The SI unit of work is newton meters or joule (J) , in honor of James Prescott Joule.

Equation: W = Fd

ENERGY

Energy is the ability to do work.

The unit of energy is Joules (J).

Two kinds of mechanical energy:a.) Potential Energyb.) Kinetic Energy

POTENTIAL ENERGY

Potential Energy is the energy possessed by a body by virtue of its position or configuration.

Two types of Potential Energy:a) Gravitationalb) Elastic

Gravitational Potential Energy

- Energy due to position.

- Equation: PE = mgh

Elastic Potential Energy

- Energy due to configuration.

- Equation: PE = ½ kx2

KINETIC ENERGY

Kinetic Energy is the energy possessed by a body because of its motion.

Equation: KE = 1/2 mv2 where m is the mass and v is the velocity.

WORK-ENERGY THEOREM

It states that the work done on an object is equal to the change in its kinetic energy.

The equation:

LAW OF CONSERVATION OF ENERGY

It states that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another.

POWER

Power is the rate of doing work.

The SI unit of power is joule per second (1 j/s) or Watt (W), in honor of James Watt.

Equation: P = W/t

APPLICATION

“How the three scalar quantities (work, energy and power) are related to each other?”

EVALUATION

Answer the following.

1.) What is the equation of work?a) Force times distanceb) Mass times distancec) Weight times distance

2.) What is the general equation of kinetic energy?a) 2/3 m/s2

b) 1/3 mv3

c) 1/2 mv2

A

C

3.) What unit is commonly used to rate motors and engines?a) wattb) horsepowerc) joule

4.) Where is the moving direction of an object if the applied force succeeds when work is done?a) parallelb) perpendicularc) proportional

B

5.) In this lesson, what was the type of energy focused?a) Chemicalb) Mechanicalc) Heat

6.) Analyze the picture. Explain how it happened.

ASSIGNMENT

Solve for the following problems and show your solutions.

1.) Armani has 73.0 kg with a speed of 16.0 m/s2 when he runs in a 100 m oval track. How much work is done?

2.) An object with a mass of 5.00 kg in raised to a height of 4 000 m. What is its GPE at this height?

3.) When you run across the corner, your weight is 50 kg in 6.5 m in 120 seconds. Find its power in watts and in horsepower.

GOD BLESS YOU ALWAYS!