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An object moving vertically is at the given heights at the specified times. Find the position equation \(s=\frac{1}{2} a t^{2}+v_{0} t+s_{0}\) for the object. At \(t=1\) second, \(s=32\) feet. At \(t=2\) seconds, \(s=32\) feet. At \(t=3\) seconds, \(s=0\) feet.

Short Answer

Expert verified
The position equation for the object is \(s=-16t^{2}+48 t +16\).

Step by step solution

01

Understand variables and given data points

The kinematic equation \(s=\frac{1}{2} a t^{2}+v_{0} t+s_{0}\) includes three unknowns: acceleration \(a\), initial velocity \(v_{0}\), and initial height \(s_{0}\). We are given three data points: at \(t=1\) second, \(s=32\) feet; at \(t=2\) seconds, \(s=32\) feet; and at \(t=3\) seconds, \(s=0\) feet.
02

Set up the equations and solve

We substitute the given data into the kinematic equation and create a system of equations. For \(t=1\) we get \(32=\frac{1}{2} a +v_{0} +s_{0}\), for \(t=2\) we get \(32=2a +2v_{0} +s_{0}\), and for \(t=3\) we get \(0=4.5a +3v_{0} +s_{0}\). Solving this system yields \(a=-32\) feet/second², \(v_{0}=48\) feet/second, and \(s_{0}=16\) feet.
03

Write out the position equation

Substituting the found values into the kinematic equation \(s=\frac{1}{2} a t^{2}+v_{0} t+s_{0}\), we find the position equation of the object: \(s=-16t^{2}+48 t +16\).

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Key Concepts

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

Acceleration
Acceleration is a fundamental concept in kinematics that refers to how an object's velocity changes over time. It is essentially the rate at which an object speeds up or slows down. For vertical motion, acceleration often involves the effects of gravity. This means objects falling to the earth accelerate downwards due to gravitational pull.
In the given problem, the unknown acceleration needs to be determined using the kinematic equation:\[ s = \frac{1}{2} a t^2 + v_0 t + s_0 \]Here, the variable \(a\) represents acceleration. By comparing the object's position at different times, we identify how rapidly its velocity is changing. In this scenario, through calculation, we find:\[ a = -32 \text{ feet/second}^2 \]The negative value represents downward acceleration due to gravity. Understanding this concept helps in predicting how quickly an object's speed will increase or decrease while moving vertically.
Initial Velocity
Initial velocity is the speed at which an object starts its motion. It dictates the initial direction and speed of the object immediately after the start time, \(t = 0\). It is crucial to know the initial velocity for calculating future positions and velocities using kinematic equations. In our kinematic equation, initial velocity is represented by \( v_0 \). For the problem, the initial velocity was determined from known positions by solving the system of equations derived from the data points:\[ s = \frac{1}{2} a t^2 + v_0 t + s_0 \]By substituting the given heights into this equation, the initial velocity is calculated as:\[ v_0 = 48 \text{ feet/second} \]This indicates that at \(t = 0\), the object had a speed of 48 feet per second in the upward direction. Initial velocity impacts how far an object will move in a given time when other forces like acceleration align.
Initial Height
Initial height tells us the vertical starting position of an object. Before any motion begins (at \(t = 0\)), the object is located at this height. Understanding initial height is essential to determine the path and landing point of the object in vertical motion.In the kinematic equation:\[ s = \frac{1}{2} a t^2 + v_0 t + s_0 \]The term \( s_0 \) represents the initial height. Having solved the equations based on provided points at different moments, we identify:\[ s_0 = 16 \text{ feet} \]This value tells us that initially, at \( t = 0 \), the object was 16 feet above the point of reference. Knowing the initial height combined with other values allows proper prediction of the object's motion trajectory.

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