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Humans can produce an output power as great as \(20 \mathrm{W} / \mathrm{kg}\) during extreme exercise. Sloths are not so energetic. At its maximum speed, a 4.0 kg sloth can climb a height of \(6.0 \mathrm{m}\) in 2.0 min. What's the specific power for this climb?

Short Answer

Expert verified
The specific power of the sloth for this climb is \(0.49 \, \mathrm{W/kg}\).

Step by step solution

01

Convert time

Firstly, the time given in minutes should be converted to seconds to align with the scientific unit of power which is expressed in watts (Joules per second). Since 1 minute is equivalent to 60 seconds, multiply the given time by 60. That is 2.0 minutes * 60 = 120 seconds.
02

Calculate the work done

Using the work done formula on an object in a gravitational field, which is work = mass × gravity × height. Substitute the given values into the formula, with the mass (m) as 4.0 kg, the acceleration due to gravity (g) as \(9.8 \, \mathrm{m/s^2}\) and the height (h) as 6.0 m. Hence, work = 4.0 kg * \(9.8 \, \mathrm{m/s^2}\) * 6.0 m = 235.2 Joules.
03

Calculate the power

The equation for power is work done over time, which is P = W / t. Substitute the calculated work and the converted time into the equation. Therefore, power = 235.2 Joules / 120 seconds = 1.96 watts.
04

Calculate the specific power

Specific power is power per unit mass. It is obtained by dividing the power by the mass of the sloth. Hence, specific power = 1.96 watts / 4.0 kg = 0.49 w/kg, which is the specific power for the climb.

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Key Concepts

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

The Work-Energy Principle
The work-energy principle is a fundamental concept in physics that states that the work done by all forces acting on an object is equal to the change in its kinetic energy. It provides a useful way to calculate the energy required to move an object from one position to another and is essential in understanding how objects interact with forces.

In the provided exercise, calculating the work done by the sloth during its climb involves using the work-energy principle. The sloth exerts a force to counteract gravity and move upwards. The work done, in this case, is gravitational work and is calculated by multiplying the mass, gravitational acceleration, and height climbed. Here, no kinetic energy change is considered as the sloth starts and ends at rest, and all the work goes into increasing the sloth's gravitational potential energy.
Power Calculation
Power in physics is defined as the rate of doing work or transferring energy. It is a measure of how quickly work can be done. The scientific unit for power is the watt, which is equivalent to one joule per second. To calculate power, you divide the work accomplished by the time it took to complete that work.

In the sloth's climb, we use the power calculation to determine how efficiently the sloth is climbing. By dividing the work done in joules by the time taken in seconds, we find the power in watts. This measure tells us how much energy the sloth expends per second to reach a height of 6.0 meters and is critical in quantifying the sloth's performance. When discussing power, ensure students understand this concept is not the total energy expended, but rather how quickly that energy is used.
Gravitational Potential Energy
Gravitational potential energy is the energy an object has due to its position in a gravitational field. This form of potential energy is crucial when dealing with heights and weights, especially when objects move vertically against the force of gravity.

For the sloth example, when it climbs, it increases its gravitational potential energy because it is moving against the force of gravity. The formula to calculate this energy gain is the same as the work done against gravity, which is mass times the gravitational acceleration times the height climbed. Understanding that gravitational potential energy is energy stored due to position and may later be converted into kinetic energy or used to do work is vital for students grasping the concept of energy conservation.

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Most popular questions from this chapter

In an amusement park water slide, people slide down an essentially frictionless tube. The top of the slide is \(3.0 \mathrm{m}\) above the bottom where they exit the slide, moving horizontally, \(1.2 \mathrm{m}\) above a swimming pool. What horizontal distance do they travel from the exit point before hitting the water? Does the mass of the person make any difference?

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