/*! 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 40 Suppose that a shot putter can p... [FREE SOLUTION] | 91Ó°ÊÓ

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Suppose that a shot putter can put a shot at the world-class speed \(v_{0}=15.00 \mathrm{~m} / \mathrm{s}\) and at a height of \(2.160 \mathrm{~m} .\) What horizontal distance would the shot travel if the launch angle \(\theta_{0}\) is (a) \(45.00^{\circ}\) and (b) \(42.00^{\circ}\) ? The answers indicate that the angle of \(45^{\circ},\) which maximizes the range of projectile motion, does not maximize the horizontal distance when the launch and landing are at different heights.

Short Answer

Expert verified
The horizontal distances are longer for angles less than 45° due to launch and landing height differences.

Step by step solution

01

Approaching the Problem with Key Equations

To find the horizontal distance, we must first use the projectile motion equations to calculate the range. The range equation we use is: \[ R = \frac{v_0 \cos(\theta_0)}{g} \left( v_0 \sin(\theta_0) + \sqrt{(v_0 \sin(\theta_0))^2 + 2gh} \right) \] where \( R \) is the horizontal range, \( v_0 = 15.00 \, \text{m/s} \) is the initial velocity, \( \theta_0 \) is the angle of launch, \( g = 9.81 \, \text{m/s}^2 \) is the acceleration due to gravity, and \( h = 2.160 \, \text{m} \) is the height.
02

Solving for the Range at 45°

Substitute \( \theta_0 = 45° \) into the range equation:First, we need to find \( \cos(45°) = \frac{\sqrt{2}}{2} \) and \( \sin(45°) = \frac{\sqrt{2}}{2} \).Then plug into the equation: \[ R_{45} = \frac{15 \times \frac{\sqrt{2}}{2}}{9.81} \left( 15 \times \frac{\sqrt{2}}{2} + \sqrt{(15 \times \frac{\sqrt{2}}{2})^2 + 2 \times 9.81 \times 2.160} \right) \]Calculate and simplify to find \( R_{45} \).
03

Solving for the Range at 42°

Now substitute \( \theta_0 = 42° \) into the range equation:First, compute \( \cos(42°) \approx 0.7431 \) and \( \sin(42°) \approx 0.6691 \).Plug these into the equation: \[ R_{42} = \frac{15 \times 0.7431}{9.81} \left( 15 \times 0.6691 + \sqrt{(15 \times 0.6691)^2 + 2 \times 9.81 \times 2.160} \right) \]Calculate and simplify to find \( R_{42} \).
04

Conclusion with Interpretation of Results

After computing the values, you will find that \( R_{45} \) and \( R_{42} \) are different. Generally, \( R_{42} \) will be longer despite the overall expectation of maximum range at 45° due to starting at a greater height, which modifies the optimal angle for maximum distance.

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Key Concepts

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

Horizontal Distance
Horizontal distance in projectile motion is the total distance a projectile covers along the horizontal axis. It is sometimes referred to as the range of the projectile. Calculating the horizontal distance involves understanding the trajectory of the projectile, which is influenced by several factors like the initial velocity, launch angle, acceleration due to gravity, and the height from which it is launched. In this particular problem, the horizontal range can be calculated using the range formula that considers a non-zero initial height of the projectile. This formula is: \[ R = \frac{v_0 \cos(\theta_0)}{g} \left( v_0 \sin(\theta_0) + \sqrt{(v_0 \sin(\theta_0))^2 + 2gh} \right) \]where:
  • \(R\) is the horizontal distance
  • \(v_0\) is the initial velocity
  • \(\theta_0\) is the launch angle
  • \(g\) is the acceleration due to gravity
  • \(h\) is the launch height
Understanding this formula is vital as it helps in taking into account the effect of the initial launch height on the projectile's range, making it crucial for accurately predicting the horizontal distance in such scenarios.
Launch Angle
The launch angle is the angle at which the projectile is launched concerning the horizontal. It plays a critical role in determining the path and distance the projectile will travel. As a general rule in physics, a launch angle of 45° is expected to provide the maximum range for a projectile when the launch and the landing happen at the same height. However, this changes when the starting height differs from the landing height. In our problem, we analyzed two specific angles, 45° and 42°. The equation shows that even if 45° is assumed to be optimal, slight variations such as a 3° reduction to 42° could result in a longer horizontal distance due to the initial height from which the projectile is launched. This happens because the height difference modifies the optimal trajectory, necessitating adjustments to the angle for maximizing distance.
Acceleration Due to Gravity
Acceleration due to gravity, denoted by \( g \), is a constant that represents the gravitational pull exerted by the Earth on objects. In most projectile motion problems close to the Earth's surface, \( g \) is approximated to be \( 9.81 \text{ m/s}^2 \). This constant affects how quickly an object speeds up when moving downward or slows down when moving upward.Gravity influences both the vertical motion and indirectly affects the horizontal distance traveled by the projectile.
  • It determines how soon the projectile will hit the ground, impacting the total time in the air.
  • This duration in the air directly influences how far the object can travel horizontally.
In projectile motion calculations, encapsulating gravity's role through the use of equations ensures that predictions about the motion, including time of flight and trajectory, are as precise as possible.
Initial Velocity
The initial velocity in projectile motion refers to the speed at which an object is launched. It breaks down into horizontal and vertical components that together determine the projectile's subsequent motion.In this scenario, the initial velocity is \( 15.00 \text{ m/s} \). This velocity is split into horizontal (\( v_0 \cos(\theta_0) \)) and vertical (\( v_0 \sin(\theta_0) \)) components:
  • The horizontal component influences how fast the projectile moves away from the launch point.
  • The vertical component impacts the maximum height the projectile reaches and contributes to the overall time of flight.
Knowing the initial velocity allows us to calculate these components accurately, helping predict how far and how high a projectile will travel given a certain launch angle and initial height.

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Most popular questions from this chapter

A light plane attains an airspeed of \(500 \mathrm{~km} / \mathrm{h}\). The pilot sets out for a destination \(800 \mathrm{~km}\) due north but discovers that the plane must be headed \(20.0^{\circ}\) east of due north to fly there directly. The plane arrives in \(2.00 \mathrm{~h}\). What were the (a) magnitude and (b) direction of the wind velocity?

A baseball leaves a pitcher's hand horizontally at a speed of \(161 \mathrm{~km} / \mathrm{h} .\) The distance to the batter is \(18.3 \mathrm{~m} .\) (a) How long does the ball take to travel the first half of that distance? (b) The second half? (c) How far does the ball fall freely during the first half? (d) During the second half? (e) Why aren't the quantities in (c) and (d) equal?

A particle \(P\) travels with constant speed on a circle of radius \(r=3.00 \mathrm{~m}\) (Fig. \(4-56\) ) and completes one revolution in \(20.0 \mathrm{~s}\). The particle passes through \(O\) at time \(t=0 .\) State the following vectors in magnitudeangle notation (angle relative to the positive direction of \(x\) ). With respect to \(O,\) find the particle's position vector at the times \(t\) of (a) \(5.00 \mathrm{~s}\), (b) \(7.50 \mathrm{~s},\) and (c) \(10.0 \mathrm{~s}\). (d) For the \(5.00 \mathrm{~s}\) interval from the end of the fifth second to the end of the tenth second, find the particle's displacement. For that interval, find (e) its average velocity and its velocity at the (f) beginning and (g) end. Next, find the acceleration at the (h) beginning and (i) end of that interval.

A frightened rabbit moving at \(6.00 \mathrm{~m} / \mathrm{s}\) due east runs onto a large area of level ice of negligible friction. As the rabbit slides across the ice, the force of the wind causes it to have a constant acceleration of \(1.40 \mathrm{~m} / \mathrm{s}^{2},\) due north. Choose a coordinate system with the origin at the rabbit's initial position on the ice and the positive \(x\) axis directed toward the east. In unit-vector notation, what are the rabbit's (a) velocity and (b) position when it has slid for 3.00 s?

Ship \(A\) is located \(4.0 \mathrm{~km}\) north and \(2.5 \mathrm{~km}\) east of ship \(B\). Ship \(A\) has a velocity of \(22 \mathrm{~km} / \mathrm{h}\) toward the south, and ship \(B\) has a velocity of \(40 \mathrm{~km} / \mathrm{h}\) in a direction \(37^{\circ}\) north of east. (a) What is the velocity of \(A\) relative to \(B\) in unit-vector notation with i toward the east? (b) Write an expression (in terms of i and \(\hat{\mathrm{j}}\) ) for the position of \(A\) relative to \(B\) as a function of \(t,\) where \(t=0\) when the ships are in the positions described above. (c) At what time is the separation between the ships least? (d) What is that least separation?

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