/*! 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 64 Useful background for this probl... [FREE SOLUTION] | 91Ó°ÊÓ

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Useful background for this problem can be found in Multiple-Concept Example \(2 .\) On a spacecraft two engines fire for a time of \(565 \mathrm{~s}\). One gives the craft an acceleration in the \(x\) direction of \(a_{x}=5.10 \mathrm{~m} / \mathrm{s}^{2},\) while the other produces an acceleration in the \(y\) direction of \(a_{y}=7.30 \mathrm{~m} / \mathrm{s}^{2} .\) At the end of the firing period, the craft has velocity components of \(v_{x}=3775 \mathrm{~m} / \mathrm{s}\) and \(v_{y}=4816 \mathrm{~m} / \mathrm{s} .\) Find the magnitude and direction of the initial velocity. Express the direction as an angle with respect to the \(+x\) axis.

Short Answer

Expert verified
The initial velocity magnitude is approximately 1903 m/s at an angle of -54 degrees from the +x-axis.

Step by step solution

01

Analyze given data

The spacecraft experiences two acceleration components: \( a_x = 5.10 \, \mathrm{m/s^2} \) in the \( x \)-direction and \( a_y = 7.30 \, \mathrm{m/s^2} \) in the \( y \)-direction. The engines fire for \( t = 565 \, \mathrm{s} \). The final velocities are \( v_x = 3775 \, \mathrm{m/s} \) and \( v_y = 4816 \, \mathrm{m/s} \). We need to find the initial velocity magnitude and direction.
02

Use kinematic equations to find initial velocities

The final velocity components can be related to the initial velocities via the equations \( v_x = v_{0x} + a_x \cdot t \) and \( v_y = v_{0y} + a_y \cdot t \). Rearrange these to find the initial velocity components: \( v_{0x} = v_x - a_x \cdot t \) and \( v_{0y} = v_y - a_y \cdot t \).
03

Calculate initial velocity components

Substitute the known values into the kinematic equations: \[ v_{0x} = 3775 \, \mathrm{m/s} - 5.10 \, \mathrm{m/s^2} \times 565 \, \mathrm{s} \] \[ v_{0y} = 4816 \, \mathrm{m/s} - 7.30 \, \mathrm{m/s^2} \times 565 \, \mathrm{s} \].Calculate these to obtain \( v_{0x} \) and \( v_{0y} \).
04

Calculate initial velocity vector magnitude

Use the initial velocity components \( v_{0x} \) and \( v_{0y} \) to find the magnitude of the initial velocity vector:\[ v_0 = \sqrt{v_{0x}^2 + v_{0y}^2} \].Substitute the values from Step 3 to obtain \( v_0 \).
05

Determine direction angle of initial velocity

The angle \( \theta \) with respect to the \( +x \)-axis can be found using:\[ \theta = \tan^{-1}\left(\frac{v_{0y}}{v_{0x}}\right) \].Substitute \( v_{0x} \) and \( v_{0y} \) to find \( \theta \).

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Key Concepts

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

Projectile Motion
Projectile motion refers to the motion of an object that is launched into the air and is subject only to gravity and air resistance. In simpler terms, whenever something is thrown, thrust, or kicked across the sky, it fits into projectile motion. When dealing with kinematics of projectiles, one needs to analyze two main components:
  • The horizontal motion, which remains consistent since only horizontal initial velocity factors in.
  • The vertical motion, which changes due to gravitational acceleration acting downwards.
In the context of a spacecraft, although we are primarily considering acceleration due to engine thrust, the idea works similarly. Here, the spacecraft has two linear accelerations acting in perpendicular directions. In step-by-step problems like the one discussed, you often start by separating the initial velocities into horizontal and vertical components. It's critical to understand how these vector components influence the overall motion trajectory and ending points. Calculating the initial velocity required using kinematic equations helps us understand the starting speed and direction a spacecraft needs to maintain its path.
Vector Analysis
Vector analysis is a powerful tool in understanding how different forces and motions interact. In the context of this problem, vectors allow us to analyze different motion aspects separately yet together—both in size and direction.
Each force or motion like a velocity or acceleration is treated as a vector having both magnitude and direction.
The initial acceleration components—being perpendicular—are effectively treated as vectors in the problem. The overall velocity vector of the spacecraft is derived considering these components. You calculate the individual velocity components and then find their resultant vector using:
  • Pythagoras' theorem to find the magnitude of the vector.
  • Trigonometric functions, which help to discern angles relative to axes.
Through the equation \[v_0 = \sqrt{v_{0x}^2 + v_{0y}^2}\]we calculate the magnitude of the velocity vector, which gives us an overall speed. And determining the direction with \[\theta = \tan^{-1}\left(\frac{v_{0y}}{v_{0x}}\right)\]gives us a comprehensive understanding of how these vectors dictate motion. For anyone working through similar problems, a strong grasp of vector basics will end up being immensely helpful.
2D Motion Analysis
Two-dimensional motion analysis requires considering movements in both horizontal and vertical directions simultaneously. This is where our knowledge of vectors and individual components comes into play. In scenarios like the one given, involving spacecraft, an object moves in the xy-plane affected by two-directional forces.
The independent treatment of horizontal and vertical components allows us to understand and predict the motion's path effectively.In this instance, the spacecraft receives acceleration in both axes which subsequently changes its velocity in both the x and y directions. Analyzing 2D motion involves:
  • Breaking down motion into respective x and y components.
  • Using kinematic equations: **\(v_x = v_{0x} + a_x \cdot t\)** and **\(v_y = v_{0y} + a_y \cdot t\)** to find initial component velocities.
  • Combining these findings to understand and predict overall movement.
This consideration allows engineers and analysts to tune spacecraft courses correctly or accurately simulate projectile paths, ensuring they meet intended targets. Deeper understanding of 2D motion becomes a valuable tool whenever actual scenarios involve complex, multi-directional movement.

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Most popular questions from this chapter

Multiple-Concept Example 4 deals with a situation similar to that presented here. A marble is thrown horizontally with a speed of \(15 \mathrm{~m} / \mathrm{s}\) from the top of a building. When it strikes the ground, the marble has a velocity that makes an angle of \(65^{\circ}\) with the horizontal. From what height above the ground was the marble thrown?

Two passenger trains are passing each other on adjacent tracks. Train A is moving east with a speed of \(13 \mathrm{~m} / \mathrm{s}\), and train \(\mathrm{B}\) is traveling west with a speed of \(28 \mathrm{~m} / \mathrm{s}\). (a) What is the velocity (magnitude and direction) of train A as seen by the passengers in train B? (b) What is the velocity (magnitude and direction) of train B as seen by the passengers in train A?

A quarterback claims that he can throw the football a horizontal distance of \(183 \mathrm{~m}\) (200 yd). Furthermore, he claims that he can do this by launching the ball at the relatively low angle of \(30.0^{\circ}\) above the horizontal. To evaluate this claim, determine the speed with which this quarterback must throw the ball. Assume that the ball is launched and caught at the same vertical level and that air resistance can be ignored. For comparison, a baseball pitcher who can accurately throw a fastball at \(45 \mathrm{~m} / \mathrm{s}(100 \mathrm{mph})\) would be considered exceptional.

A jetliner can fly 6.00 hours on a full load of fuel. Without any wind it flies at a speed of \(2.40 \times 10^{2} \mathrm{~m} / \mathrm{s} .\) The plane is to make a round-trip by heading due west for a certain distance, turning around, and then heading due east for the return trip. During the entire flight, however, the plane encounters a \(57.8-\mathrm{m} / \mathrm{s}\) wind from the jet stream, which blows from west to east. What is the maximum distance that the plane can travel due west and just be able to return home?

Two cannons are mounted as shown in the drawing and rigged to fire simultaneously. They are used in a circus act in which two clowns serve as human cannonballs. The clowns are fired toward each other and collide at a height of \(1.00 \mathrm{~m}\) above the muzzles of the cannons. Clown A is launched at a \(75.0^{\circ}\) angle, with a speed of \(9.00 \mathrm{~m} / \mathrm{s}\). The horizontal separation between the clowns as they leave the cannons is \(6.00 \mathrm{~m} .\) Find the launch speed \(v_{0 B}\) and the launch angle \(\theta_{B}\left(>45.0^{\circ}\right)\) for clown B.

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