/*! 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 31 The point from where a ball is p... [FREE SOLUTION] | 91Ó°ÊÓ

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The point from where a ball is projected is taken as the ori-gin of the coordinate axes. The \(x\) and \(y\) components of its displacement are given by \(x=6 t\) and \(y=8 t-5 t^{2} .\) What is the velocity of projection? a. \(6 \mathrm{~m} / \mathrm{s}\) b. \(8 \mathrm{~m} / \mathrm{s}\) c. \(10 \mathrm{~m} / \mathrm{s}\) d. \(14 \mathrm{~m} / \mathrm{s}\)

Short Answer

Expert verified
The velocity of projection is 10 m/s.

Step by step solution

01

Understanding Displacement Functions

The displacement as a function of time for each coordinate is given by two equations: the displacement along the x-axis is described by \(x = 6t\) and along the y-axis by \(y = 8t - 5t^2\). These equations allow us to determine the initial velocity components.
02

Calculate x-component of Velocity

The x-component of velocity \(v_x\) is the derivative of \(x\) with respect to time. Since \(x = 6t\), \(v_x = \frac{dx}{dt} = 6\).
03

Calculate y-component of Velocity at t=0

The initial y-component of velocity \(v_{y0}\) is the derivative of \(y\) with respect to time, evaluated at \(t = 0\). From \(y = 8t - 5t^2\), we have \(v_y = \frac{dy}{dt} = 8 - 10t\). At \(t = 0\), \(v_{y0} = 8\).
04

Calculate Initial Velocity Magnitude

The initial velocity \(v\) is the vector sum of the x and y components of velocity. Using the Pythagorean theorem, we have: \(v = \sqrt{v_x^2 + v_{y0}^2} = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100} = 10\).

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Key Concepts

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

Projectile Motion
Projectile motion involves the movement of an object through the air, following a curved path under the influence of gravity. This path is typically a parabola. When you throw or launch an object, it becomes a projectile. An important aspect of projectile motion is its independence from horizontal and vertical movements, allowing these two components to be analyzed separately.
In the context of our exercise, the path of the ball is determined by its initial velocity and the influence of gravity. This gives rise to distinct mathematical equations for motion in horizontal and vertical directions. Understanding the path involves two main movements:
  • Horizontal Motion: Uniform motion with constant velocity, because there is no acceleration affecting it horizontally.
  • Vertical Motion: It's subject to gravitational acceleration, resulting in an upward motion that slows, stops at the peak, and accelerates downwards.
The mathematical modeling of such motion typically includes parametric equations that establish the positions along the x- and y-axis. These allow us to determine various characteristics, such as initial velocities and projectile path equations.
Velocity Components
In projectile motion, the velocity can be broken down into two components: horizontal and vertical. These are called velocity components.
The horizontal component of the velocity remains unchanged throughout the motion because there is no acceleration in the horizontal direction in the idealized model. In contrast, the vertical component evolves over time due to gravity.
In our specific problem, we dissected the velocity into its horizontal and vertical components:
  • Horizontal Component: The equation for horizontal displacement was given as \(x = 6t\). Here, the x-component of the velocity is simply \(6\) m/s, derived by taking the derivative \(\frac{dx}{dt} \).
  • Vertical Component: For the vertical motion \(y = 8t - 5t^2\), its velocity component \(v_y\) at any time \(t\) is \(8 - 10t\). At the start, when \(t = 0\), the vertical component is \(8\) m/s.
By examining these components individually, one can understand the projectile's initial movements in both directions.
Initial Velocity Calculation
The initial velocity of a projectile is a critical attribute that needs to be computed for in-depth analysis of its motion. It represents the vector sum of the velocity components and gives a comprehensive picture of the motion initiation.
When calculating the initial velocity, use the formula that combines both components into a single magnitude:
  • The initial horizontal velocity is already known as \(v_x = 6\) m/s.
  • Similarly, the initial vertical velocity is \(v_{y0} = 8\) m/s.
  • These components are combined using the Pythagorean theorem because they are perpendicular to each other. Thus, the initial velocity \(v\) is expressed as \(v = \sqrt{v_x^2 + v_{y0}^2}\).
For our problem, substitute the known values: \(v = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100} = 10\) m/s.
Factoring these calculations helps in understanding how fast and in which direction the projectile was initially launched.

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Most popular questions from this chapter

A body of mass \(m\) is projected horizontally with a velocity \(v\) from the top of a tower of height \(h\) and it reaches the ground at a distance \(x\) from the foot of the tower. If a second body of mass \(2 \mathrm{~m}\) is projected horizontally from the top of a tower of height \(2 h\), it reaches the ground at a distance \(2 x\) from the foot of the tower. The horizontal velocity of the second body is a. \(v\) b. \(2 v\) c. \(\sqrt{2} v\) d. \(v / 2\)

Two tall buildings are \(30 \mathrm{~m}\) apart. The speed with which a ball must be thrown horizontally from a window \(150 \mathrm{~m}\) above the ground in one building so that it enters a window \(27.5 \mathrm{~m}\) from the ground in the other building isa. \(2 \mathrm{~m} / \mathrm{s}\) b. \(6 \mathrm{~m} / \mathrm{s}\) c. \(4 \mathrm{~m} / \mathrm{s}\) d. \(8 \mathrm{~m} / \mathrm{s}\)

An airplane moving horizontally with a speed of \(180 \mathrm{~km} / \mathrm{h}\) drops a food packet while flying at a height of \(490 \mathrm{~m}\). The horizontal range of the food packet is \(\left(g=9.8 \mathrm{~m} / \mathrm{s}^{2}\right)\) a. \(180 \mathrm{~m}\) b. \(980 \mathrm{~m}\) c. \(500 \mathrm{~m}\) d. \(670 \mathrm{~m}\)

A car is going in south with a speed of \(5 \mathrm{~m} / \mathrm{s}\). To a man sitting in car a bus appears to move towards west with a speed of \(2 \sqrt{6} \mathrm{~m} / \mathrm{s}\). What is the actual speed of the bus? a. \(4 \mathrm{~ms}^{-1}\) b. \(3 \mathrm{~ms}^{-1}\)c. \(7 \mathrm{~ms}^{-1}\) d. None of these

A ball is thrown at different angles with the same speed \(u\) and from the same point and it has the same range in both the cases. If \(y_{1}\) and \(y_{2}\) be the heights attained in the two cases, then \(y_{1}+y_{2}\) is equal to a. \(\frac{u^{2}}{g^{2}}\) b. \(\frac{2 u^{2}}{g}\) c. \(\frac{u^{2}}{2 g}\) d. \(\frac{u^{2}}{4 g}\)

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