/*! 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 56 As a protest against the umpire'... [FREE SOLUTION] | 91Ó°ÊÓ

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As a protest against the umpire's calls, a baseball pitcher throws a ball straight up into the air at a speed of \(20.0 \mathrm{~m} / \mathrm{s}\). In the process, he moves his hand through a distance of \(1.50 \mathrm{~m}\). If the hall has a mass of \(0.150 \mathrm{~kg}\), find the force he exerts on the ball to give it this upward speed.

Short Answer

Expert verified
The pitcher exerts a force of \(10 \mathrm{N}\) on the ball.

Step by step solution

01

Identify the initial velocity, final velocity, and distance

According to the problem, the initial velocity (u) of the ball is 0 m/s, the final velocity (v) is 20 m/s, and the distance through which the pitcher moves his hand (s) is 1.50 m.
02

Use the equation of motion

Let's use the third equation of motion \(v^2 = u^2 + 2as\) to find the acceleration. According to this equation, \(20^2 = 0^2 + 2*a*1.5\). Solving for \(a\), we find that the acceleration (a) is \(200/3 \mathrm{m/s}^2\).
03

Use Newton's second law

According to Newton's second law, force (F) equals mass (m) multiplied by acceleration (\(a\)). In this case, \(F = m*a\). Substituting the given mass (0.150 kg) and the calculated acceleration (\(200/3 \mathrm{m/s}^2\)), we find that the pitcher exerts a force of \(10 \mathrm{N}\) on the ball to give it an upward speed of \(20 \mathrm{m/s}\).

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Key Concepts

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

Equations of Motion
Understanding equations of motion is essential for solving problems involving the movement of objects. They describe the relationship between an object's velocity, acceleration, distance traveled, and time taken. In the given exercise, we deal with an object, a baseball, being thrown vertically upward.

We used the third equation of motion, which is expressed as \(v^2 = u^2 + 2as\), where \(v\) represents the final velocity, \(u\) the initial velocity, \(a\) the acceleration, and \(s\) the distance covered. These equations are derived from the constant acceleration formulas and are extremely helpful for evaluating the motion of objects when the acceleration is constant, as in the case of gravity acting on the baseball.

To solve the problem, we substituted the known values into the third equation to find the acceleration. The initial velocity (when the pitcher starts to move his hand) is zero and the final velocity is given as \(20.0 \mathrm{~m/s}\), with a displacement of \(1.50 \mathrm{~m}\). Understanding and appropriately applying equations of motion can efficiently help us determine missing variables in similar physics problems.
Newton's Second Law
Newton's second law of motion is a cornerstone of classical mechanics and can be succinctly stated as \(F=ma\), where \(F\) is the force applied to an object, \(m\) is the object's mass, and \(a\) is its acceleration. The law essentially tells us that the force exerted on an object is directly proportional to the acceleration it experiences and is also directly proportional to the object's mass.

In the context of the baseball problem, after determining the ball's acceleration using the equations of motion, we applied Newton's second law to find the force. By plugging the mass of the ball and the computed acceleration into the formula, we were able to calculate that the pitcher exerted a force of \(10 \mathrm{N}\) to reach a final velocity of \(20 \mathrm{m/s}\) over a displacement of \(1.50 \mathrm{m}\).

This law is pivotal for understanding how forces affect the motion of objects and is particularly useful for exploring the dynamics of objects in various scenarios, including the vertical motion of objects under the influence of gravity or the forces exerted in a game of baseball.
Kinematics
Kinematics is the branch of physics concerned with the motion of objects without considering the forces that cause this motion. It provides us with the tools to describe an object's position, speed, velocity, and acceleration over time. Key kinematic quantities include displacement, time, velocity, and acceleration, which are interconnected by kinematic equations.

When analyzing the problem of the baseball's vertical throw, kinematics allows us to predict subsequent motion of the ball after being subjected to a force. It involves understanding the initial conditions of the ball's movement and how these conditions are transformed into its velocity and position over the duration of its flight.

Kinematic equations are vital for comprehending the motion of objects launched or thrown in various contexts, such as sports or celestial bodies moving in space. Knowing how to interpret and apply these equations is an invaluable skill when venturing into more complex areas of physics.

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Most popular questions from this chapter

A coin is placed near one edge of a book lying on a table, and that edge of the book is lifted until the coin just slips down the incline as shown in Figure \(\mathrm{P} 4,70\). The angle of the incline, \(\theta_{c}\), called the critical angle, is measured. (a) Draw a frec-body diagram for the coin when it is on the verge of slipping and identify all forces acting on it. Your free- body diagram should include a force of static friction acting up the incline. (b) Is the magnitude of the friction force equal to \(\mu_{3} n\) for angles less than \(\theta_{c}\) ? Explain. What can you definitely say about the magnitude of the friction force for any angle \(\theta \leq \theta_{c} ?\) (c) Show that the coefficient of static friction is given by \(\mu_{\mathrm{s}}=\tan \theta_{c}\). (d) Once the coin starts to slide down the incline, the angle can be adjusted to a new value \(\theta_{c}^{\prime} \leq \theta_{c}\) such that the coins moves down the incline with constant speed. How does observation enable you to obtain the coefficient of kinetic friction?

The air exerts a forward force of \(10 \mathrm{~N}\) on the propeller of a \(0.20-\mathrm{kg}\) model airplane. If the plane accelerates forward at \(2.0 \mathrm{~m} / \mathrm{s}^{2}\), what is the magnitude of the resistive force exerted by the air on the airplane?

The force exerted by the wind on the sails of a sailboat is 390 Nnorth. The water exerts a force of 180 Neast. If the boat (including its crew) has a mass of \(270 \mathrm{~kg}\), what are the magnitude and direction of its acceleration?

A sled weighing \(60.0 \mathrm{~N}\) is pulled horizontally across snow so that the coefficient of kinetic friction between sled and snow is \(0.100, \overline{\mathrm{A}}\) penguin weighing \(70.0 \mathrm{~N}\) rides on the sled, as in Figtire \(\mathrm{P} 4.78\). If the coefficient of static friction between penguin and sled is \(0.700\), find the maximum horizontal force that can be exerted on the sled before the penguin begins to slide off.

An object of mass \(m\) is dropped from the roof of a building of height \(h .\) While the object is falling, a wind blowing parallel to the face of the building exerts a constant horizontal force \(F\) on the object. (a) How long does it take the object to strike the ground? Express the time \(t\) in terms of \(g\) and \(h\) (b) Find an expression in terms of \(m\) and \(F\) for the acceleration \(a_{x}\) of the object in the horizontal direction (taken as the positive \(x\) -direction). (c) How far is the object displaced horizontally before hitting the ground? Answer in terms of \(m, g, F_{t}\) and \(h\). \((d)\) Find the magnitude of the object's acceleration while it is falling, using the variables \(F, m\), and \(g\).

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