/*! 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 86 Two soccer players, Mia and Alic... [FREE SOLUTION] | 91Ó°ÊÓ

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Two soccer players, Mia and Alice, are running as Alice passes the ball to Mia. Mia is running due north with a speed of 6.00 \(\mathrm{m} / \mathrm{s} .\) The velocity of the ball relative to Mia is 5.00 \(\mathrm{m} / \mathrm{s}\) in a direction \(30.0^{\circ}\) east of south. What are the magnitude and direction of the velocity of the ball relative to the ground?

Short Answer

Expert verified
The velocity of the ball is 3.00 m/s at 56.3° east of north.

Step by step solution

01

Define the Problem

We need to find the magnitude and direction of the velocity of the ball relative to the ground. We know Mia's velocity as well as the velocity of the ball relative to her motion. Let's use vector analysis to solve it.
02

Determine Mia's Velocity Vector

Mia is running due north at a speed of 6.00 m/s. Let's denote Mia's velocity vector as \( \vec{v}_M = 6.00 \hat{j} \ \mathrm{m/s} \), where \( \hat{j} \) is a unit vector pointing north.
03

Break Down Ball's Relative Velocity

The velocity of the ball relative to Mia is 5.00 m/s at an angle 30.0 degrees east of south. We need to find its components:- Southward component: \( 5.00 \cos(30.0^{\circ}) = 5.00 (\frac{\sqrt{3}}{2}) \approx 4.33 \ \mathrm{m/s} \) (south direction is negative \( \hat{j} \))- Eastward component: \( 5.00 \sin(30.0^{\circ}) = 5.00 (0.5) = 2.50 \ \mathrm{m/s} \) (east direction is \( \hat{i} \)).Thus, the relative velocity vector \( \vec{v}_{BM} = -4.33 \hat{j} + 2.50 \hat{i} \ \mathrm{m/s} \).
04

Calculate the Ball's Absolute Velocity

The ball's velocity relative to the ground \( \vec{v}_B \) can be calculated using the vector sum of Mia's velocity \( \vec{v}_M \) and the ball’s velocity relative to Mia \( \vec{v}_{BM} \):\[\vec{v}_B = \vec{v}_M + \vec{v}_{BM} = 6.00 \hat{j} + (-4.33 \hat{j} + 2.50 \hat{i})\]Simplifying, we get:\[\vec{v}_B = 2.50 \hat{i} + 1.67 \hat{j} \ \mathrm{m/s}\]
05

Find the Magnitude of the Velocity

The magnitude of \( \vec{v}_B \) is calculated using the Pythagorean theorem:\[\| \vec{v}_B \| = \sqrt{(2.50)^2 + (1.67)^2} \approx \sqrt{6.25 + 2.78} \approx \sqrt{9.03} \approx 3.00 \ \mathrm{m/s}\]
06

Determine the Direction of the Velocity

To find the direction, calculate the angle \( \theta \) east of north using the tangent ratio:\[\tan \theta = \frac{2.50}{1.67}\]\[\theta = \tan^{-1} \left(\frac{2.50}{1.67}\right) \approx \tan^{-1} (1.50)\approx 56.3^{\circ}\]
07

Conclusion

The velocity of the ball relative to the ground is 3.00 m/s at an angle of approximately 56.3 degrees east of north.

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Key Concepts

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

Relative Velocity
Relative velocity is the measure of the velocity of one object as observed from another moving object. In our problem, we calculate the velocity of the soccer ball relative to Mia, who is also in motion. This approach is useful in scenarios where both the observer and the object of interest are moving.

In the context of this exercise, you first determine the velocity of the ball with respect to Mia. Then, you use this information to find the velocity of the ball relative to the ground. The relative velocity vector, in this case, becomes a crucial step in determining the final answer. It takes into account both Mia's movement and the ball's path relative to her, allowing us to calculate the absolute velocity of the ball in relation to a fixed point, which is the ground in this scenario.
Velocity Components
Breaking down a velocity into its components is essential for analyzing its effect in different directions. In vector analysis, we understand movements in terms of north-south (vertical or y-direction) and east-west (horizontal or x-direction).

For this problem, the ball's velocity relative to Mia was given at an angle. To simplify calculations, we split this velocity into two perpendicular components:
  • Southward (vertical): calculated using cosine for the southern component.
  • Eastward (horizontal): calculated using sine for the eastern component.
By separating these components, we enable easier integration of this velocity with Mia’s velocity to find the total velocity from the perspective of the ground.
Pythagorean Theorem
The Pythagorean theorem is a fundamental principle used to calculate the magnitude of a resultant vector when its components are known. In the context of our exercise, we were given the components of the ball's velocity with respect to the ground.

The formula used is: \[\| \vec{v}_B \| = \sqrt{(2.50)^2 + (1.67)^2}\]This formula helps us find the absolute magnitude of the resultant velocity vector by applying the square root of the sums of the squared components. This step is crucial to determine how fast the ball is moving from the ground's point of view. This step gives the result in meters per second, providing a clear understanding of the ball's speed.
Tangent Ratio
The tangent ratio is a trigonometric function used to find angles when two sides of a right triangle are known. It is particularly useful in vector analysis when determining the direction of a vector.

For this exercise, once the components of the velocity vector were known, you can determine the direction angle \(\theta\) using:\[\tan \theta = \frac{2.50}{1.67}\]The angle \(\theta\) is then found using the inverse tangent function:\[\theta = \tan^{-1} \left(\frac{2.50}{1.67}\right)\]This process results in an angle within the first quadrant, demonstrating how the tangent ratio helps in defining direction in polar form from known vector components. This allows you to present the velocity not just as a magnitude but also as a direction relative to a given axis, enhancing the understanding of the ball’s trajectory.

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Most popular questions from this chapter

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