/*! 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 6 Dave Johnson, the bronze medalis... [FREE SOLUTION] | 91Ó°ÊÓ

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Dave Johnson, the bronze medalist at the 1992 Olympic decathlon in Barcelona, leaves the ground at the high jump with vertical velocity component \(6.00 \mathrm{m} / \mathrm{s}\). How far does his center of mass move up as he makes the jump?

Short Answer

Expert verified
The center of mass of Dave moves up by approximately \( 1.84 m \) during the jump.

Step by step solution

01

Identifying given values

The first step is always to identify the given values from the problem. Here, the only value given is the vertical velocity component which is \(6.00 m/s\). The acceleration due to gravity is a known constant which is \(9.8 m/s^2\).
02

Applying the formula to calculate the height

With these values, you can apply the formula \( h = v^2 / 2g \) to find the height. So, it will be \( h = (6.00 m/s)^2 / 2(9.8 m/s^2) \).
03

Evaluating the result

Evaluate the above expression to find the height. That gives you the distance the center of mass would move up during the jump.

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Key Concepts

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

Kinematics
Kinematics is the branch of physics that describes the motion of objects without considering the forces that cause the motion. When solving kinematics problems, we usually find quantities like displacement, velocity, and acceleration using algebraic equations. In the high jump problem, we focused on the vertical motion of the athlete's center of mass.

Kinematic equations are derived from the constant acceleration formulas, where time, displacement, and velocity are related. Given that we know the initial vertical velocity (\(6.00 \text{ m/s}\)) and the acceleration due to gravity (\(9.8 \text{ m/s}^2\)), we can determine how high Dave's center of mass traveled during the jump. This type of motion can be considered as a part of a projectile motion, which we will explain further in the next section.
Projectile Motion
Projectile motion is a form of motion where an object moves in a curved trajectory under the influence of gravity. It is important to note that the only force acting on the projectile (if we neglect air resistance) is gravity. In our example, the upward journey of the high jumper can be seen as projectile motion.

The jumper's center of mass moves upward and then downward in a symmetrical parabolic path. The highest point of this path is where the velocity component in the vertical direction is zero, which is also the peak of the jump. By calculating the height reached at this peak, we solve an essential part of the projectile motion problem. We treat the motion in the vertical direction separately from the horizontal, applying kinematic equations independently for each direction.
Acceleration due to Gravity
Acceleration due to gravity is the acceleration gained by an object because of the gravitational force of Earth. This acceleration has a standard value of approximately \(9.8 \text{ m/s}^2\) near the Earth's surface and it acts in the downward direction, towards the center of the Earth.

In our high jump problem, gravity plays a significant role in the jumper's motion. It is what accelerates the jumper back down after reaching the peak of the jump. Using the value of the acceleration due to gravity, we can determine the height reached, as seen in the formula \( h = \frac{v^2}{2g} \) where \( h \) is the height, \( v \) is the initial vertical velocity, and \( g \) stands for the acceleration due to gravity. The negative sign is often included to indicate the acceleration is downwards; however, in this formula, we use the magnitude of the values to calculate the height reached.

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Most popular questions from this chapter

A block of mass \(M\) rests on a table. It is fastened to the lower end of a light vertical spring. The upper end of the spring is fastened to a block of mass \(m .\) The upper block is pushed down by an additional force \(3 m g\), so the spring compression is \(4 \mathrm{mg} / \mathrm{k}\). In this configuration the upper block is released from rest. The spring lifts the lower block off the table. In terms of \(m,\) what is the greatest possible value for \(M ?\)

A toy cannon uses a spring to project a \(5.30-\mathrm{g}\) soft rubber ball. The spring is originally compressed by \(5.00 \mathrm{cm}\) and has a force constant of \(8.00 \mathrm{N} / \mathrm{m}\). When the cannon is fired, the ball moves \(15.0 \mathrm{cm}\) through the horizontal barrel of the cannon, and there is a constant friction force of \(0.0320 \mathrm{N}\) between the barrel and the ball. (a) With what speed does the projectile leave the barrel of the cannon? (b) At what point does the ball have maximum speed? (c) What is this maximum speed?

Air moving at \(11.0 \mathrm{m} / \mathrm{s}\) in a steady wind encounters a windmill of diameter \(2.30 \mathrm{m}\) and having an efficiency of \(27.5 \% .\) The energy generated by the windmill is used to pump water from a well \(35.0 \mathrm{m}\) deep into a tank \(2.30 \mathrm{m}\) above the ground. At what rate in liters per minute can water be pumped into the tank?

At time \(t_{i},\) the kinetic energy of a particle is \(30.0 \mathrm{J}\) and the potential energy of the system to which it belongs is \(10.0 \mathrm{J}\) At some later time \(t\), the kinetic energy of the particle is 18.0 J. (a) If only conservative forces act on the particle, what are the potential energy and the total energy at time \(t_{f} ?\) (b) If the potential energy of the system at time \(t_{f}\) is \(5.00 \mathrm{J},\) are there any nonconservative forces acting on the particle? Explain.

A \(75.0-\mathrm{kg}\) skysurfer is falling straight down with terminal speed \(60.0 \mathrm{m} / \mathrm{s} .\) Determine the rate at which the skysurfer- Earth system is losing mechanical energy.

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