/*! 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 74 A racing car, starting from rest... [FREE SOLUTION] | 91Ó°ÊÓ

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A racing car, starting from rest, travels around a circular turn of radius \(23.5 \mathrm{m}\). At a certain instant, the car is still accelerating, and its angular speed is \(0.571 \mathrm{rad} / \mathrm{s}\). At this time, the total acceleration (centripetal plus tangential) makes an angle of \(35.0^{\circ}\) with respect to the radius. (The situation is similar to that in Interactive Figure \(8.12 b .\) ) What is the magnitude of the total acceleration?

Short Answer

Expert verified
The total acceleration magnitude is approximately 9.38 m/s².

Step by step solution

01

Understand the Problem

The car is moving around a circular track with a given radius and angular speed. The total acceleration of the car is given to form an angle with the radius. We need to determine the magnitude of this total acceleration.
02

Analyze the Components of the Total Acceleration

The total acceleration consists of two components: 1. Tangential acceleration (\(a_t\)): Responsible for the change in speed along the path of the car. 2. Centripetal acceleration (\(a_c\)): Responsible for keeping the car in circular motion. It acts perpendicular to the tangential acceleration, pointing towards the center.
03

Calculate Centripetal Acceleration

Centripetal acceleration \(a_c\) is given by the formula \(a_c = r \cdot \omega^2\), where \(r = 23.5\) m and \(\omega = 0.571\) rad/s. Calculate \(a_c\).\[a_c = 23.5 \times (0.571)^2 = 7.6705 \, \text{m/s}^2\]
04

Use Trigonometry to Find Tangential Acceleration

The angle between the total acceleration and the radius is given, so we can use trigonometric functions to find the tangential component:\[\tan(\theta) = \frac{a_t}{a_c}\]where \(\theta = 35.0^\circ\). Solve for \(a_t\).\[a_t = a_c \cdot \tan(35.0^\circ) = 7.6705 \times \tan(35) = 5.3695 \, \text{m/s}^2\]
05

Calculate the Magnitude of the Total Acceleration

Now, use the Pythagorean theorem to find the magnitude of the total acceleration:\[a = \sqrt{a_c^2 + a_t^2}\]Substitute the values of \(a_c\) and \(a_t\) to find \(a\).\[a = \sqrt{(7.6705)^2 + (5.3695)^2} = 9.3841 \, \text{m/s}^2\]
06

Conclusion

The magnitude of the total acceleration of the racing car while it is on the circular turn is approximately \(9.38 \, \text{m/s}^2\).

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Key Concepts

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

Centripetal Acceleration
In circular motion, centripetal acceleration is a key concept. It is the acceleration directed towards the center of the circular path and is responsible for changing the direction of the velocity of an object moving along a path. This acceleration ensures the object remains in a curved path rather than moving off in a straight line.

To calculate centripetal acceleration (\(a_c\)), we use the formula:
  • \(a_c = r \cdot \omega^2\)
where:
  • \(r\) = radius of the circle
  • \(\omega\) = angular speed in radians per second
In our problem, the radius \(r\) is given as \(23.5\) meters and the angular speed \(\omega\) is \(0.571\) rad/s. Plugging these values into the formula gives us:\[a_c = 23.5 \times (0.571)^2 = 7.6705\, \text{m/s}^2\]Centripetal acceleration is crucial as it doesn’t influence the speed but keeps the car on its circular trajectory by continually adjusting its direction.
Tangential Acceleration
Tangential acceleration is related to the change in speed of an object moving along its circular path. Unlike centripetal acceleration which changes the direction, tangential acceleration increases or decreases the speed of the object as it moves along the path.

To determine tangential acceleration (\(a_t\)), we often rely on the relationship between the components of acceleration when an angle is involved. Given the angle \(\theta\) between the total acceleration and the radius, we can use the tangent function from trigonometry:
  • \(\tan(\theta) = \frac{a_t}{a_c}\)
Given that \(\theta = 35.0^\circ\) and \(a_c = 7.6705\, \text{m/s}^2\), we find:
  • \[a_t = 7.6705 \times \tan(35.0^\circ) = 5.3695\, \text{m/s}^2\]
Tangential acceleration thus complements the centripetal component by changing the speed, working together to define the path and speed of the object in motion.
Trigonometry
Trigonometry serves as an essential tool when analyzing circular motion, especially when there are angles involved. In our exercise, the angle between the total acceleration vector and the radius of the circle brings trigonometry into play for determining the separate components of the total acceleration.

With the given angle (\(35.0^\circ\)) between the total acceleration and the radius, trigonometric functions help in expressing the relationship between centripetal and tangential accelerations:
  • The tangent function is particularly instrumental:\[\tan(\theta) = \frac{a_t}{a_c}\]
This works because in the right triangle formed by these vectors, the opposite side is the tangential acceleration, and the adjacent side is the centripetal acceleration.

Additionally, after finding the individual components, the Pythagorean theorem helps synthesize these into the net or total acceleration:
  • \[a = \sqrt{a_c^2 + a_t^2}\]
Trigonometry not only facilitates calculating the unknown components but also fundamentally connects these elements in circular motion. Understanding how trigonometric principles apply to motions helps to resolve vectors into manageable components, offering clearer insight into complex motions.

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Most popular questions from this chapter

A top is a toy that is made to spin on its pointed end by pulling on a string wrapped around the body of the top. The string has a length of \(64 \mathrm{cm}\) and is wound around the top at a spot where its radius is \(2.0 \mathrm{cm} .\) The thickness of the string is negligible. The top is initially at rest. Someone pulls the free end of the string, thereby unwinding it and giving the top an angular acceleration of \(+12 \mathrm{rad} / \mathrm{s}^{2} .\) What is the final angular velocity of the top when the string is completely unwound?

Two Formula One racing cars are negotiating a circular turn, and they have the same centripetal acceleration. However, the path of car A has a radius of \(48 \mathrm{m},\) while that of car \(\mathrm{B}\) is \(36 \mathrm{m} .\) Determine the ratio of the angular speed of car A to the angular speed of car B.

A car is traveling along a road, and its engine is turning over with an angular velocity of \(+220 \mathrm{rad} / \mathrm{s} .\) The driver steps on the accelerator, and in a time of \(10.0 \mathrm{s}\) the angular velocity increases to \(+280 \mathrm{rad} / \mathrm{s}\). (a) What would have been the angular displacement of the engine if its angular velocity had remained constant at the initial value of \(+220 \mathrm{rad} / \mathrm{s}\) during the entire \(10.0-\mathrm{s}\) interval? (b) What would have been the angular displacement if the angular velocity had been equal to its final value of \(+280 \mathrm{rad} / \mathrm{s}\) during the entire \(10.0-\mathrm{s}\) interval? (c) Determine the actual value of the angular displacement during the \(10.0-\) s interval.

Conceptual Example 2 provides some relevant background for this problem. A jet is circling an airport control tower at a distance of \(18.0 \mathrm{km}\) An observer in the tower watches the jet cross in front of the moon. As seen from the tower, the moon subtends an angle of \(9.04 \times 10^{-3}\) radians. Find the distance traveled (in meters) by the jet as the observer watches the nose of the jet cross from one side of the moon to the other.

A motorcyclist is traveling along a road and accelerates for \(4.50 \mathrm{s}\) to pass another cyclist. The angular acceleration of each wheel is \(+6.70 \mathrm{rad} / \mathrm{s}^{2},\) and, just after passing, the angular velocity of each wheel is \(+74.5 \mathrm{rad} / \mathrm{s},\) where the plus signs indicate counterclockwise directions. What is the angular displacement of each wheel during this time?

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