/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 38 You are told that the gravitatio... [FREE SOLUTION] | 91Ó°ÊÓ

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You are told that the gravitational potential energy of a \(2.0-\mathrm{kg}\) object has decreased by \(10 \mathrm{~J} .\) (a) With this information, you can determine (1) the object's initial height, (2) the object's final height, (3) both the initial and the final height, (4) only the difference between the two heights. Why? (b) What can you say has physically happened to the object?

Short Answer

Expert verified
We can determine only the difference between the heights: \(0.51 \, \mathrm{m}\). The object has descended, losing potential energy.

Step by step solution

01

Identify What Information is Given

We know that the gravitational potential energy has decreased by \(10 \, \mathrm{J}\). The mass of the object is \(m = 2.0 \, \mathrm{kg}\), and we use the gravitational acceleration \(g = 9.8 \, \mathrm{m/s^2}\).
02

Understand Potential Energy Formula

Gravitational potential energy is given by the formula \(U = mgh\), where \(m\) is mass, \(g\) is gravitational acceleration, and \(h\) is height. The change in potential energy is \(\Delta U = mg\Delta h\).
03

Solve for Height Difference

Given that the potential energy change \(\Delta U = 10 \, \mathrm{J}\) and mass \(m = 2.0 \, \mathrm{kg}\), solve for \(\Delta h\): \[ \Delta U = mg\Delta h \Rightarrow 10 = 2.0 \times 9.8 \times \Delta h \]\[ \Delta h = \frac{10}{19.6} \approx 0.51 \, \mathrm{m} \]
04

Interpret Result for Part (a)

With the given information, we can determine only the difference between the two heights, which is \(0.51 \, \mathrm{m}\). We cannot determine the initial or the final heights individually because we have no information about either height.
05

Explain Physical Scenario for Part (b)

The object has moved downward, reducing its potential energy. This indicates that it has fallen or descended by \(0.51 \, \mathrm{m}\). Without additional information, we know that its height decreased, but not exactly how far it initially started or ended up.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Physics Problem-Solving
Grasping physics problems often involves breaking down complex ideas into simpler, more manageable steps. This method allows for a clear understanding and solution of the problem at hand.

When tackling problems like the one mentioned, it is important to start with identifying what information you already have. Write down all the given data, which in this case includes the object's mass (2.0 kg) and the decrease in gravitational potential energy (10 J).

Next, it's crucial to use relevant physics principles and formulas to bridge the gap between what you know and what you need to discover. Distill the problem into core components—like understanding that potential energy changes due to height changes—and apply scientific formulas to find specific answers. Breaking the problem down into step-by-step solutions not only helps in understanding but also in explaining it effectively to others.
Potential Energy Formula
The potential energy formula is foundational in physics, especially concerning gravitational forces. Gravitational potential energy (U) is expressed as \( U = mgh \), where:
  • \( m \) represents the mass of the object in kilograms (kg)
  • \( g \) denotes the acceleration due to gravity (approximated as 9.8 m/s\(^2\) on Earth's surface)
  • \( h \) is the height above a reference point in meters (m)

In situations involving change, we consider the difference in potential energy: \( \Delta U = mg\Delta h \). Here, \( \Delta h \) is the change in height. If the energy decreases by a certain amount, we can determine the corresponding height difference. Understanding this formula allows us to unravel various physical scenarios, be it an object being dropped, lifted, or sliding down a slope.
Height Difference Calculation
Height difference calculation is a common application of the potential energy formula, providing practical insights into real-life physics scenarios. Knowing the potential energy change \( \Delta U \) of an object and its mass \( m \), we aim to find how much its height \( \Delta h \) has altered.

The formula \( \Delta U = mg\Delta h \) can be rearranged to solve for height difference: \[ \Delta h = \frac{\Delta U}{mg} \]Applying the details from our example, where \( \Delta U = 10 \, \mathrm{J} \) and \( m = 2.0 \, \mathrm{kg} \), leads us to:\[ \Delta h = \frac{10}{2.0 \times 9.8} = \frac{10}{19.6} \approx 0.51 \, \mathrm{m} \]
This shows that the object descended roughly 0.51 meters, showcasing how height calculation clarifies energy changes in physical movements. Each problem instance provides a unique insight into mechanics, enhanced by precise calculations.

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Most popular questions from this chapter

A hot-air balloon ascends at a constant rate. (a) The weight of the balloon does (1) positive work, (2) negative work, (3) no work. Why? (b) A hot-air balloon with a mass of \(500 \mathrm{~kg}\) ascends at a constant rate of \(1.50 \mathrm{~m} / \mathrm{s}\) for \(20.0 \mathrm{~s}\). How much work is done by the upward buoyant force? (Neglect air resistance.)

To measure the spring constant of a certain spring, a student applies a 4.0 - \(\mathrm{N}\) force, and the spring stretches by \(5.0 \mathrm{~cm} .\) What is the spring constant?

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An out-of-control truck with a mass of \(5000 \mathrm{~kg}\) is traveling at \(35.0 \mathrm{~m} / \mathrm{s}\) (about \(80 \mathrm{mi} / \mathrm{h}\) ) when it starts descending a steep \(\left(15^{\circ}\right)\) incline. The incline is icy, so the coefficient of friction is only \(0.30 .\) Use the work-energy theorem to determine how far the truck will skid (assuming it locks its brakes and skids the whole way) before it comes to rest.

A race car is driven at a constant velocity of \(200 \mathrm{~km} / \mathrm{h}\) on a straight, level track. The power delivered to the wheels is \(150 \mathrm{~kW}\). What is the total resistive force on the car?

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