UNIT 1: Mechanics and Materials_JAN 2023_2

The formula for calculating the gravitational potential energy in an object is shown above. Which object will have the largest value for its GPE

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What are Equations for Gravitational Potential Energy?

• Gravitational Potential Energy = Mass x Gravitational Field Strength x Height

• Gravitational Potential Energy = Weight x Height

• Gravitational Potential Energy = Mass x Gravitational Field Strength / Height

• Gravitational Potential Energy = Weight / Height

An object is speeding up when: (Choose All That Apply) (May have to choose more than 1 to be right)

• it is gaining kinetic energy.

• it is losing kinetic energy.

• it is gaining gravitational potential energy.

• it is losing gravitational potential energy.

The sum of the kinetic and potential energy in a system is known as the system's _____________________ energy.

• mechanical

• chemical

• thermal

• combined

Sentence: "And just so you know, this could be different kinds of potential energy, be it gravitational or elastic. However, for this video, we'll just be looking at the gravitational potential energy."

a. What types of potential energy are mentioned?

• • i. Gravitational only

• • ii. Elastic only

• • iii. Both gravitational and elastic

• • iv. Nuclear and magnetic

"The key concept we need to understand in this lesson is that, just like the law of conservation of energy says, the mechanical energy in a closed system is always conserved. This means that even though the kinetic energy might change and the potential energy might change, the total sum of these two don't change. That is, energy simply transforms from one type to the other; if one goes up, the other goes down."

a. What is the key concept explained in this lesson?

• • i. Conservation of kinetic energy

• • ii. Conservation of potential energy

• • iii. Conservation of mechanical energy

• • iv. Conservation of elastic energy

If the kinetic energy changes will it have any effect on mechanical Energy?

• No
• Maybe
• Not sure
• Yes

In a closed system with only mechanical energy, which of the following is true?

• (a) Potential energy can only decrease while kinetic energy increases.

• (b) Potential energy can only increase while kinetic energy decreases.

• (c) Potential and kinetic energy can both increase simultaneously.

• (d) Potential and kinetic energy can both decrease simultaneously.

• (e) Potential energy simply transforms into kinetic energy.

What will happen if kinetic energy increases in a closed system?

• The temperature of the closed system will decrease.
• The volume of the closed system will decrease.
• The pressure within the closed system will decrease.
• The potential energy will decrease

Sentence: "So let's say we have a ball that starts on the ground. We then launch it into the air by giving it 100 joules of kinetic energy. If we want to apply energy conservation to the ball, we first need to calculate its total mechanical energy by adding the kinetic energy and the gravitational potential energy. The kinetic energy is given to us; it's a hundred joules, but we still need the GPE."

a. What do we need to calculate first when applying energy conservation to the ball?

• • i. Gravitational potential energy

• • • ii. Elastic potential energy

• • • iii. Total mechanical energy

• • iv. Kinetic energy