/*! 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 4 The current indoor world record ... [FREE SOLUTION] | 91Ó°ÊÓ

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The current indoor world record time in the \(200-\mathrm{m}\) race is \(19.92 \mathrm{~s}\), held by Frank Fredericks of Namibia (1996), while the indoor record time in the one-mile race is \(228.5 \mathrm{~s}\), held by Hicham El Guerrouj of Morroco (1997). Find the mean speed in meters per second corresponding to these record times for (a) the \(200-\mathrm{m}\) event and (b) the one-mile event.

Short Answer

Expert verified
The mean speed for the 200-m event is approximately \(10.04 \mathrm{m/s}\) and for the one-mile event is approximately \(7.04 \mathrm{m/s}\).

Step by step solution

01

Compute the speed for the 200-m event

The speed for the 200-m event can be calculated directly, using the formula for speed. This is because the distance and time are both given in compatible units (meters and seconds). So, the speed is calculated by dividing the distance by time, which is \(200 \mathrm{m} / 19.92 \mathrm{s} = 10.04 \mathrm{m/s}\).
02

Convert miles to meters

The distance for the one-mile event is given in miles, while the target is to get the speed in meters per second. So, the distance must first be converted from miles to meters. Remember that 1 mile equals approximately 1609.34 meters.
03

Compute the speed for the one-mile event

Now that the distance has been converted to meters, the speed for a mile is calculated similarly to the previous step - by dividing the distance by time. So, the speed is calculated as follows: \(1609.34 \mathrm{m} / 228.5 \mathrm{s} = 7.04 \mathrm{m/s}\).

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Key Concepts

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

Kinematics in Physics
Kinematics is a branch of physics that describes the motion of points, objects, and systems of bodies without considering the forces that caused the motion. A key part of kinematics is understanding the relationships between speed, velocity, distance, and time.

In our exercise, kinematics is applied to determine the mean speed of two different races. The mean speed is a simple concept in kinematics, defined as the total distance traveled divided by the time it takes to cover that distance. The record times in athletics provide a practical example of how kinematics is used to compare performances in different events.
Unit Conversion
Unit conversion is crucial in many areas of science and everyday life. It is the process of converting the value of a physical quantity from one unit to another.

In the context of our exercise, we encounter a unit conversion when dealing with the one-mile race. As the speed must be calculated in meters per second, we convert the distance from miles to meters. Knowing that 1 mile is equivalent to approximately 1609.34 meters helps us perform this conversion accurately. This step is vital to ensure that the calculated speed is meaningful and comparable across different measurements.

Why is Unit Conversion Important?

Understanding unit conversion ensures that data is consistent and helps in comparing different systems of measurement. It is a fundamental skill in physics and engineering that allows us to navigate between various scales, from microscopic to cosmic.
Speed Formula Application
Applying the speed formula is an example of putting kinematic equations to practical use. The basic formula for speed, mean speed in particular, is calculated as the total distance traveled divided by the total time taken. The formula can be represented as \(\text{Speed} = \frac{\text{Distance}}{\text{Time}}\).

In our example, the speed formula is applied to calculate the mean speed for both the 200-m event and the one-mile event. For the 200-m event, both distance and time are given in compatible units, which makes the application straightforward. However, in the one-mile event, it showcases the necessity for unit conversion before applying the speed formula to obtain the answer in a consistent unit of meters per second.

Real-World Implications

Understanding and applying the speed formula is invaluable not only in academic settings but also in real life, such as in transportation, where it helps in calculating travel times and ensuring safety speeds.

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Most popular questions from this chapter

A ball is thrown upward from the ground with an initial speed of \(25 \mathrm{~m} / \mathrm{s}\); at the same instant, another ball is dropped from a building \(15 \mathrm{~m}\) high. After how long will the balls be at the same height?

A stuntman sitting on a tree limb wishes to drop vertically onto a horse galloping under the tree. The constant speed of the horse is \(10.0 \mathrm{~m} / \mathrm{s}\), and the man is initially \(3.00 \mathrm{~m}\) above the level of the saddle. (a) What must be the horizontal distance between the saddle and the limb when the man makes his move? (b) How long is he in the air?

A model rocket is launched straight upward with an initial speed of \(50.0 \mathrm{~m} / \mathrm{s}\). It accelerates with a constant upward acceleration of \(2.00 \mathrm{~m} / \mathrm{s}^{2}\) until its engines stop at an altitude of \(150 \mathrm{~m}\). (a) What can you say about the motion of the rocket after its engines stop? (b) What is the maximum height reached by the rocket? (c) How long after liftoff does the rocket reach its maximum height? (d) How long is the rocket in the air?

A certain car is capable of accelerating at a rate of \(0.60 \mathrm{~m} / \mathrm{s}^{2}\) How long does it take for this car to go from a speed of \(55 \mathrm{mi} / \mathrm{h}\) to a speed of \(60 \mathrm{mi} / \mathrm{h}\) ?

BIO Colonel John P. Stapp, USAF, participated in studying whether a jet pilot could survive emergency ejection. On March 19,1954 , he rode a rocketpropelled sled that moved down a track at a speed of \(632 \mathrm{mi} / \mathrm{h}\) (see Fig. P2.56). He and the sled were safely brought to rest in \(1.40 \mathrm{~s}\). Determine in SI units (a) the negative acceleration he experienced and (b) the distance he traveled during this negative acceleration.

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