WORKWhat is work ? is an abstract idea related to energy. when work is done it is accompanied by

a change in energy. a work is done when a force applied

and distance travelled by an object is the same direction.

is the product of force and distance.

• W = Fdwhere, F = Force (N)

d = distance (m)

Is there a work done?

A girl pushing a chair

Is there a work done?

A boy pushing a wall

Is there a work done?

A waiter carrying a tray

Work is done when the force (F) applied to the object causes the object to have a displacement (d) in the same direction as the force applied. The symbol for work is a capital W. The work done by a force can be calculated as:

W = Fd

where, F = Force,

d = distance

Calculating Work

Suppose a woman is pushing a grocery cart with a 500 Newton force along the 7 meters aisle, how much work is done in pushing the cart from one end of the aisle to the other?

Calculating Work

Given:Force = 500 Ndistance = 7

mWork = ?

Solution:

Solve the following problems:1. Alvin kick a stone and it moves 5 m. If he

applies 51 N, how much work he have spend on the stone?

2. A laborer brings 2 bag of cement up to the second floor of the building. In each bag, he applies 230 N. If the height from 1st floor to the 2nd floor is 10 m, what is the work of the laborer?

3. A dump truck spends 150000 N bringing a full load of sugarcane from Poblacion to URSUMCO. If the distance from Poblacion to URSUMCO is 35,000 m, how much work spent?

Work is a method of transferring energy

A ball and a plastic bottle

Work is a method of transferring energy

A ball and a plastic bottle

Is there a work done on the ball?

Work is a method of transferring energy

A ball and a plastic bottle

What can a moving ball do?

Work is a method of transferring energyThe moving ball contains “something” that can move the empty bottle when hit. The moving ball does work on the empty bottle.

That something is what we call energy.

After the ball hits the empty bottle, what happened?

The ball losses energy and the empty bottle gains it, that is the transfer of energy.

Is the energy of a moving body or Energy of motion

From Greek word kinetikos, means movingIn quantifying energy of motion we have the equation:

KE = , where m = mass

v = velocityKE of an object depends on its mass and velocity.

Kinetic Energy (KE)

Kinetic Energy (KE)A 1000 kg car has a velocity of 17m/s. What is the car’s kinetic energy?

Given:

m = 1000 kg

v = 17 m/s

Solution: KE = KE = KE = KE = )KE = KE =

Match the two Columns A with Column B:

Column B___1. If you want to

increase the kinetic energy of an object, you must increase its ____and _____

___2. It is the ability to do work

___3. It means moving___4. It is the energy of

motion___5. Energy is the ability

to do ___.

Column A

a. Workb. Energyc. Kinetic Energyd. mass and

acceleratione. kinetikos

Solve the following:Johnny runs at the speed of 3 m/s. If he has a mass of 65 kg, what would be his Kinetic Energy?

After kicking, the soccer ball rush up to the speed of 16 m/s. What would be the ball’s kinetic energy if the ball has mass of 0.75kg?

A 750 kg ambulance rush to the speed of 25 m/s. What does the ambulance Kinetic Energy.

Solve the following:A man and a bicycle have a total mass of 75 kg, if the speed of the man and the bicycle is 5 m/s, what would be the KE?

After batting, the 0.25 kg ball rush up to the speed of 15 m/s. What would be the ball’s kinetic energy?

A 1500 kg jeepney runs at the speed of 20 m/s. What does the jeepney’s Kinetic Energy?

Commonly known as energy at restAlso called Gravitational Potential EnergyAn object gains energy when raised from the ground and loses energy when made to fall

In equation, PE = where: m = mass

g = acceleration due to

gravity

h = height

Potential Energy (PE)

Potential Energy (PE)

A Man lifting a box

0.5 m

2 kg

Given: d = 0.5 mg = m = 2 kg

PE = ?Solution: PE = mgh

= (0.5m)(= (4.9(2kg)= 9.8 Nm= 9.8 J

1. What would be the PE of a 0.5 kg ball raised up to a height from the ground of 20 m?

2. What would be the PE of a 5 kg book put onto a shelves with a height of 3.5 m?

3. A 10 kg case of coke is at the top of the delivery truck. If the height of the truck is 5 m. What would be the PE of the case of coke?

4. A 0.15 kg cellphone is place on a table. If the table is 0.5 m, what would be the PE of the phone?

5. A 0.5 kg tray is carried by a waiter. If the tray is 1.5 m above the floor, what would be its PE?

Solve the following for (PE)

Match the two Columns A with Column B:

Column B

___1. It is energy at rest

___2. It is the ability to do work

___3. It means moving___4. It is the energy of

motion___5. An acceleration

of an object due to gravity.

Column A

a. 9.8 b. Energyc. Kinetic Energyd. Potential Energye. kinetikos

1. A 0.15 kg cellphone is place on a table. If the table is 0.5 m, what would be the PE of the phone?

2. A 0.5 kg tray is carried by a waiter. If the tray is 1.5 m above the floor, what would be its PE?

3. After batting, the 0.25 kg ball rush up to the speed of 15 m/s. What would be the ball’s kinetic energy?

4. A 1500 kg jeepney runs at the speed of 20 m/s. What does the jeepney’s Kinetic Energy?

Solve the following for (PE)