Lesson 2- Mechanical Energy

The energy that an object has because of its position, shape, or chemical composition.

• Work

• Potential energy

• Mechanical energy

Tags

NGSS.MS-PS3-2

The sum of an object's kinetic and potential energies. PE + KE= ME

• Work

• Potential energy

• Mechanical energy

The transfer of energy to an object by using a force that causes the object to move in the direction of the force.

• Work

• Potential energy

• Mechanical energy

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Describe the transformation (changes energy type) of mechanical energy in a ball when it is thrown straight up and then comes back down.

• It begins with potential energy, as the ball goes up the kinetic energy increases and the potential energy decreases. When the ball reaches the top, the potential energy increases and kinetic energy decreases. As it comes back down, potential energy decreases and kinetic energy increases

• The potential energy and kinetic energy doesn't change as the ball moves up and down

• The ball has kinetic energy when it's held, and when the ball is tossed up the potential increases and the kinetic energy decreases, and then when it comes down the kinetic decreases and the potential energy also decreases

Tags

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Is mechanical energy conserved (stored) as a playground swing moves?

• Yes, because mechanical energy is conserved as the swing moves back and forth.

• No because some of the energy transfers to the air and some energy transforms into other types of energy. But the total energy is conserved.

• Yes, mechanical energy is always the same.

• The swing will keep moving as the energy changes from potential and kinetic energy

Tags

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Describe the two forms of energy that make up the mechanical energy that make up the mechanical energy of an object.

• Nuclear energy and electrical energy make up mechanical energy

• Mechanical energy is made up of sound energy and thermal energy.

• Mechanical energy is made up of potential energy and kinetic energy

Tags

NGSS.MS-PS3-2

What can you determine about mechanical energy from the graph?

• As potential energy increases, the kinetic energy also increases

• As the total energy stays the same, kinetic energy increases as potential energy decreases

• The total energy goes up and down as potential and kinetic energy changes

• As kinetic energy changes, the potential energy changes so that the total energy changes

Tags

NGSS.MS-PS3-4

This graph shows the energy transformations of an ideal pendulum system. How does this differ from a real-world example?

• A real world pendulum would perform exactly as this pendulum

• A real world pendulum would have more kinetic energy

• A real world pendulum would have decreasing potential and kinetic energies as the pendulum would slow down and eventually stop

• A real world pendulum would have more total energy over time than this ideal pendulum

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-2

NGSS.MS-PS3-5

Brianna pushes against a door that is stuck and does not move. Describe the mechanical energy of the door in terms of force, energy, and work.

• No work was done because even though she used force in trying to open the door, the door did not move

• Some work was done because she used energy and tried to force the door open

• She used energy and force so when she tried to open the door, she applied to work on the door

• Brianna found out later that it wasn't a door that she was pushing on, but it was the wall of the classroom

Pablo lifts a bag of flour 0.8 m from the floor to the table. He lifted the bag using a force of 20 N. How much work did Pablo do on the bag of flour?

• 24 J

• 16 J

• 0.8 J

• 20 J

Tags

NGSS.MS-PS3-5