/*! 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 45 The rocket-driven sled \(\textit... [FREE SOLUTION] | 91Ó°ÊÓ

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The rocket-driven sled \(\textit{Sonic Wind No. 2,}\) used for investigating the physiological effects of large accelerations, runs on a straight, level track 1070 m (3500 ft) long. Starting from rest, it can reach a speed of 224 m/s(500 mi/h) in 0.900 s. (a) Compute the acceleration in m/s\(^2\), assuming that it is constant. (b) What is the ratio of this acceleration to that of a freely falling body (\(g\))? (c) What distance is covered in 0.900 s? (d) A magazine article states that at the end of a certain run, the speed of the sled decreased from 283 m/s (632 mi/h) to zero in 1.40 s and that during this time the magnitude of the acceleration was greater than 40\(g\). Are these figures consistent?

Short Answer

Expert verified
(a) 248.89 m/s² (b) 25.38 times (c) 100.02 m (d) No, they are not consistent.

Step by step solution

01

Understanding the given data

Start by identifying and listing the data given in the problem. For Part (a), you have initial velocity \( u = 0 \) m/s, final velocity \( v = 224 \) m/s, and time \( t = 0.900 \) s. For Part (d), the initial velocity \( v_i = 283 \) m/s, final velocity \( v_f = 0 \) m/s, and time \( t = 1.40 \) s.
02

Compute the acceleration (a)

To find the acceleration, use the equation \( v = u + at \). Since \( u = 0 \), the equation simplifies to \( a = \frac{v}{t} \). Substitute the known values to get \( a = \frac{224 \, \text{m/s}}{0.900 \, \text{s}} \). Calculate to find \( a \).
03

Solve Part (a)

Plug the values into the equation: \( a = \frac{224}{0.900} = 248.89 \) m/s\(^2\).
04

Calculate the acceleration ratio (b)

For the ratio of this acceleration to the acceleration due to gravity \( g \), use \( g = 9.81 \, \text{m/s}^2 \). The ratio is \( \frac{a}{g} = \frac{248.89}{9.81} \). Compute the result.
05

Solve Part (b)

The ratio is \( \frac{248.89}{9.81} \approx 25.38 \).
06

Calculate the distance covered (c)

Use the equation \( s = ut + \frac{1}{2}at^2 \). With \( u = 0 \), it simplifies to \( s = \frac{1}{2} \times 248.89 \times (0.900)^2 \). Find \( s \) by substituting and calculating.
07

Solve Part (c)

Calculate: \( s = \frac{1}{2} \times 248.89 \times 0.81 = 100.02 \) meters.
08

Analyze Part (d) scenario

Use the same formula \( a = \frac{v_f - v_i}{t} \) for deceleration with \( v_f = 0 \), \( v_i = 283 \) m/s, and \( t = 1.40 \) s. Calculate \( a \).
09

Solve Part (d)

Plug in the values: \( a = \frac{0 - 283}{1.40} = -202.14 \) m/s\(^2\). Calculate the magnitude and compare it to \( 40g = 40 \times 9.81 = 392.4 \) m/s\(^2\).
10

Determine consistency of figures

Compare \( 202.14 \) m/s\(^2\) with \( 392.4 \) m/s\(^2\). The magnitude of the calculated deceleration is less than \( 40g \), so the figures are not consistent.

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Key Concepts

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

Acceleration Calculation
In physics, acceleration refers to how quickly an object changes its speed. It can be speeding up, slowing down, or changing direction. For our problem, we're dealing with an acceleration from rest to a high speed over a short period. Understanding acceleration is crucial because it tells us how fast something is moving in a given direction and how rapidly it's reaching that speed. In mathematical terms, acceleration (\( a \)) can be calculated using the formula:
  • \[ a = \frac{v - u}{t} \]
where:
  • \( v \) is the final velocity
  • \( u \) is the initial velocity
  • \( t \) is the time taken
For instance, in the case of the Sonic Wind No. 2 sled, the acceleration was calculated as\( 248.89 \text{ m/s}^2 \), which illustrates a very rapid increase in speed.Finding these values can help track the performance and safety of high-speed vehicles and is useful for understanding the intense forces experienced in rapid acceleration situations.
Motion Equations
Motion equations are fundamental in solving problems related to the movement of objects. When an object moves, whether it's a sled or a car, understanding these equations helps us predict where it will be at a given time.One key equation to remember is:
  • \[ s = ut + \frac{1}{2}at^2 \]
Here:
  • \( s \) represents distance
  • \( u \) is initial velocity
  • \( a \) is acceleration
  • \( t \) is time
This equation helps determine the distance covered in a specific timeframe, assuming constant acceleration. It's invaluable for calculating travel distances, as seen when the sled covers approximately 100 meters in 0.900 seconds.These formulas provide a framework to comprehend complex motion scenarios, including how far an object travels or how conditions impact speed over time.
Deceleration Analysis
Deceleration is simply negative acceleration, meaning the object slows down. Analyzing deceleration involves the same physics concepts, just applied in reverse. In critical situations like emergency stops, calculating deceleration accurately is crucial. To find deceleration, the same formula for acceleration can be used:
  • \[ a = \frac{v_f - v_i}{t} \]
For instance, when the sled's speed decreased from 283 m/s to a complete stop in 1.40 seconds, the calculated deceleration was\( -202.14 \text{ m/s}^2 \).Notice the negative sign indicating reduction in speed.It's important to compare deceleration rates to known standards, such as the force of gravity (\( g \)), to confirm the data's feasibility. Despite the reported figures, a deceleration value of less than \( 40g \) was not consistent, highlighting the importance of accurate calculations for safe and efficient vehicle operation.

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