Understanding Potential Energy: The Car and Electromagnet Scenario

If an electromagnet holds a 1,500-kg car at a height of 25 m, which statement is false after a power outage?

• A. The car had a potential energy of 367.5 kJ.
• B. 367.5 kJ of potential energy is converted to kinetic energy.
• C. The car still has a potential energy of 367.5 kJ when it hits the ground.
• D. The potential energy is converted to kinetic energy and then to sound energy.

Answer: (C)

The statement that the car still has a potential energy of 367.5 kJ when it hits the ground is indeed false because potential energy is defined as the energy stored in an object due to its height above the ground. Once the car descends to the ground, its height effectively becomes zero, which means its potential energy also becomes zero. Before the power outage, when the car is suspended at a height of 25 m, its potential energy can be calculated using the formula \( PE = mgh \), where \( m \) is the mass in kilograms (1,500 kg), \( g \) is the acceleration due to gravity (approximately 9.81 m/s²), and \( h \) is the height in meters (25 m). Performing the calculation yields a potential energy of approximately 367.5 kJ. After a power outage, if the electromagnet fails, the car will begin to fall. As it falls, the potential energy is converted into kinetic energy, which can be described by the conversion of energy principles. When the car hits the ground, all of the potential energy is transformed into kinetic energy, assuming negligible air resistance until it reaches the ground. Additionally, when the car strikes the ground, some

When studying for the National League for Nursing (NLN) Science Practice Exam, grasping fundamental concepts like potential energy and kinetic energy is key. Let’s break down an intriguing scenario involving a powerful electromagnet suspended 1,500 kg of metal—a car, at a height of 25 meters. Picture it: you’re at the edge of your seat, and that car is hanging there, just waiting for something to happen!

Here’s the crux: if a power outage occurs, what might happen to that car? The question is not just hypothetical; it’s a perfect example of potential energy at play. Before the lights go out, the car hangs there with a potential energy of about 367.5 kJ, calculated using the formula ( PE = mgh ) (where ( m ) is mass, ( g ) is the acceleration due to gravity, and ( h ) is height).

Now, I know what you're thinking: 'But what happens once the power goes out?' Well, once that electromagnet releases its grip, gravity takes over, and the car begins its fall. Here’s where it gets interesting: as it descends, the stored potential energy transforms into kinetic energy—the energy of motion. It’s like the universe saying, “You’re going to move now!”

So, let's address the statements posed in the earlier question. The false statement here is that the car still has a potential energy of 367.5 kJ when it hits the ground. That’s simply not true! As soon as the car reaches the ground level, its height is zero, which means its potential energy is also zero.

Now, you might wonder: Why does this matter? Well, understanding these energy transformations is crucial not just for physics, but for nursing as well. Think about it: nurses often need to apply scientific principles daily, whether that’s in assessing falls or administering medications!

If you take just one thing away from this discussion, let it be the idea that energy is always shifting. When the car hit the ground, all that stored energy has rapidly converted into kinetic energy and, quite literally, dispersed as sound energy—the crash of metal upon impact. Isn’t it fascinating how energy moves and changes form?

To clarify: Potential energy is all about the height, and once that car hits the ground, we say goodbye to its potential energy. It’s now part of the kinetic world, where speed and motion reign.

Understanding this process isn’t just about acing exams; it’s about making sense of the world around us. And as you prepare for the NLN exam, considering how these scientific principles connect can help solidify your knowledge.

So, as you review potential and kinetic energy, remember this scenario with the car. Not only does it highlight physics principles, but it also encourages you to contemplate the other connections within your field! Keep pushing forward; you’re on the right track!