/*! 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 46 In basketball, hang is an illusi... [FREE SOLUTION] | 91Ó°ÊÓ

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In basketball, hang is an illusion in which a player seems to weaken the gravitational acceleration while in midair. The illusion depends much on a skilled player's ability to rapidly shift the ball between hands during the flight, but it might also be supported by the longer horizontal distance the player travels in the upper part of the jump than in the lower part. If a player jumps with an initial speed of \(v_{0}=7.00 \mathrm{~m} / \mathrm{s}\) at an angle of \(\theta_{0}=35.0^{\circ}\), what percent of the jump's range does the player spend in the upper half of the jump (between maximum height and half maximum height)?

Short Answer

Expert verified
Approximately 69.7% of the jump's range is spent in the upper half.

Step by step solution

01

Calculate the Time to Maximum Height

To find the time to reach maximum height, we need to calculate the vertical component of the initial velocity and use the kinematic equation. The vertical component of the velocity \(v_{0y}\) is given by \(v_{0y} = v_{0}\sin(\theta)\).Let's calculate it:\[v_{0y} = 7.00\sin(35^{\circ}) = 7.00(0.5736) \approx 4.0152 \text{ m/s}\]The time \(t_h\) to reach the maximum height is given by:\[ t_h = \frac{v_{0y}}{g} = \frac{4.0152}{9.81} \approx 0.409\text{ s} \]
02

Calculate the Maximum Height

We use the kinematic equation to find the maximum height:\[ h = \frac{v_{0y}^2}{2g} \]Substituting:\[ h = \frac{4.0152^2}{2 \times 9.81} \approx \frac{16.121}{19.62} \approx 0.822 \text{ m} \]
03

Calculate the Time for Half Maximum Height

To find the time to reach half the maximum height (\(h/2\)), use the equation:\[ h/2 = v_{0y} t - \frac{1}{2}gt^2 \]Set \( h/2 = 0.822/2 \approx 0.411 \text{ m} \):\[ 0.411 = 4.0152t - 4.905t^2 \]This is a quadratic equation: \(4.905t^2 - 4.0152t + 0.411 = 0\).Using the quadratic formula \(t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\):- \(a = 4.905\)- \(b = -4.0152\)- \(c = 0.411\)Find the relevant positive root for the ascent to half the maximum height.
04

Solve the Quadratic Equation

Plug in values to find \(t\):\[t = \frac{4.0152 \pm \sqrt{4.0152^2 - 4 \times 4.905 \times 0.411}}{2 \times 4.905}\]Calculate \(b^2 - 4ac\):\[4.0152^2 - 4 \times 4.905 \times 0.411 = 16.121 - 8.046 = 8.075\]Find the positive root:\[t = \frac{4.0152 \pm \sqrt{8.075}}{9.81}\]Compute \(\sqrt{8.075} \approx 2.842\):\[t = \frac{4.0152 + 2.842}{9.81} \approx 0.694 \text{ s} \]Subtract \(t_h\) from this to find the time between half maximum height and maximum: \(0.694 - 0.409 = 0.285 \text{ s}\).
05

Calculate Total Time for Full Ascent

Double the time to reach maximum height for the total jump duration:\[ T = 2t_h = 2 \times 0.409 = 0.818 \text{ s} \]
06

Calculate Time in Upper Half of Jump

The total time in the upper half of the jump is the time between half maximum height to maximum plus the descent time equivalent (upper descent time is equal to the upper ascent time):\[ \text{Upper half duration} = 2 \times 0.285 = 0.57 \text{ s} \]
07

Calculate Percentage of Range in Upper Half

Since the horizontal distance is covered uniformly, the percentage of the range in the upper half of the jump is the ratio of the upper half time over total jump time:\[ \frac{0.57}{0.818} \times 100\% \approx 69.7\% \]

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Key Concepts

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

Kinematic Equations
Kinematic equations play a crucial role in understanding and solving problems related to projectile motion. These equations describe the motion of objects under the action of constant acceleration. In our case, the acceleration is due to gravity, which acts downward with a magnitude of approximately 9.81 m/sThe kinematic equations that govern projectile motion allow us to calculate various characteristics, such as time, distance, velocity, and more. Specifically, we utilize the following fundamental equations:
  • For vertical motion: \[ v_{y} = v_{0y} - gt \]\[ h = v_{0y} t - \frac{1}{2}gt^2 \]
  • For horizontal motion: \[ x = v_{0x} t \]The horizontal velocity \(v_{0x}\) remains constant during the motion.
In the context of the basketball jump problem, applying the kinematic equations helps us deduce the times at different stages of the jump, such as reaching maximum height and returning to lower heights. Understanding these stages is crucial for breaking down complex projectile motion problems into simpler, manageable parts.
Vertical Velocity Component
The vertical velocity component is a vital concept when analyzing projectile motion. It represents the portion of the initial velocity that influences the vertical motion of the object. For an object launched at an angle, you can calculate this component using the sine function:\[ v_{0y} = v_{0} \sin(\theta_{0}) \]The value depends on both the initial speed \(v_{0}\) and the launch angle \(\theta_{0}\).
In our exercise, the vertical component of the initial velocity was found to be approximately 4.0152 m/s, calculated using the initial speed of 7.00 m/s and the angle of 35.0°.This vertical component is crucial for determining how high the projectile will rise and how long it will stay in the air. By knowing \(v_{0y}\), we can easily compute the time it takes for the object to reach its maximum height and other essential information regarding its vertical trajectory.
Quadratic Equation
Solving quadratic equations is a common requirement in projectile motion problems. When determining when an object reaches specific points in its trajectory, such as half the maximum height, the problem often boils down to solving a quadratic equation.This type of equation takes the form:\[ at^2 + bt + c = 0 \]In many projectile problems, the coefficients \(a\), \(b\), and \(c\) are derived from kinematic equations.Solving for time \(t\) in these cases utilizes the quadratic formula:\[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]This formula provides two solutions, typically representing different points in the projectile's path, and selecting the correct solution (often the positive one) is critical to determining the stage of the motion in question.
In our original exercise, applying the quadratic formula allowed us to find the times to reach half the maximum height accurately, thus enabling the understanding of the player's hang time illusion.

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Most popular questions from this chapter

For women's volleyball the top of the net is \(2.24 \mathrm{~m}\) above the floor and the court measures \(9.0 \mathrm{~m}\) by \(9.0 \mathrm{~m}\) on each side of the net. Using a jump serve, a player strikes the ball at a point that is \(3.0 \mathrm{~m}\) above the floor and a horizontal distance of \(8.0 \mathrm{~m}\) from the net. If the initial velocity of the ball is horizontal, (a) what minimum magnitude must it have if the ball is to clear the net and (b) what maximum magnitude can it have if the ball is to strike the floor inside the back line on the other side of the net?

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