/*! 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 107 ssm mmh The drawing shows Robin ... [FREE SOLUTION] | 91Ó°ÊÓ

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ssm mmh The drawing shows Robin Hood (mass 77.0 \(\mathrm{kg}\)) about to escape from a dangerous situation. With one hand, he is gripping the rope that holds up a chandelier (mass 195 \(\mathrm{kg}\)). When he cuts the rope where it is tied to the floor, the chandelier will fall, and he will be pulled up toward a balcony above. Ignore the friction between the rope and the beams over which it slides, and find (a) the acceleration with which Robin is pulled upward and (b) the tension in the rope while Robin escapes.

Short Answer

Expert verified
The upward acceleration is 4.25 m/s², and the rope tension is 1081.62 N.

Step by step solution

01

Understanding the Problem

Robin Hood is holding onto a rope that is holding a chandelier. When the rope is cut, the chandelier falls and Robin is pulled up. We need to find Robin's upward acceleration and the tension in the rope.
02

Applying Newton's Second Law to the System

The chandelier and Robin are part of a connected system. When the rope is cut, they both accelerate due to gravity. We can model this using Newton's Second Law. For the system:- Chandelier's downward force is its weight: \( F_{c} = m_{c}g \).- Robin's upward force is his weight: \( F_{r} = m_{r}g \).- The net force \( F_{net} \) on the system is the difference of these weights because it translates the effect of the chandelier's fall into Robin's acceleration upwards. The equation for the system is:\[ F_{net} = m_{c}g - m_{r}g = (m_{c} - m_{r})g \].The acceleration \( a \) is then given by:\[ F_{net} = (m_{c} + m_{r}) a \].
03

Calculating Robin's Acceleration

Substituting the given values into the formula:- Chandelier mass: \( m_{c} = 195 \) kg, Robin's mass: \( m_{r} = 77 \) kg.- Gravitational acceleration: \( g = 9.81 \) m/s².\[ a = \frac{m_{c}g - m_{r}g}{m_{c} + m_{r}} \]\[ a = \frac{195 \times 9.81 - 77 \times 9.81}{195 + 77} \]Calculate the numbers:\[ a = \frac{1911.45 - 755.37}{272} \approx 4.25 \text{ m/s²} \].The acceleration with which Robin is pulled upward is \( 4.25 \) m/s².
04

Finding the Tension in the Rope

The tension in the rope must balance Robin's weight and provide the acceleration calculated earlier:- The force required to accelerate Robin: \( F_a = m_{r}a \).- His weight: \( m_{r}g \).- Tension, \( T \), in the rope is thus: \( T = m_{r}g + F_a \).Substitute the known quantities:\[ T = 77 \times 9.81 + 77 \times 4.25 \]Calculate:\[ T = 754.37 + 327.25 \approx 1081.62 \text{ N} \].The tension in the rope while Robin escapes is approximately \( 1081.62 \text{ N} \).

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Key Concepts

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

Force and Motion
When an object is in motion or at rest, it is influenced by forces, which are pushes or pulls upon it. The fundamental concept to understand here is that forces cause changes in motion. Newton's Second Law of Motion provides the framework for how forces affect motion. It tells us that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. This is expressed in the formula:\[ F = ma \]where \( F \) is the net force, \( m \) is the mass of the object, and \( a \) is its acceleration. In the given scenario, when Robin Hood cuts the rope, the chandelier falls, and simultaneously, the force due to gravity on the chandelier causes a net force that accelerates Robin upwards. The force causing Robin to accelerate is part of the same force pulling the chandelier down, highlighting the interconnected nature of forces and motion in this system.
Acceleration
Acceleration is the rate of change of velocity of an object. In simpler terms, it's how quickly an object speeds up or slows down. For Robin Hood, acceleration plays a crucial role in determining how fast he moves upward once the rope is cut. The acceleration is calculated using Newton's Second Law as it applies to the entire system (Robin and the chandelier).To find Robin's upward acceleration, we calculate the net force on the system, which is the difference in gravitational force between the chandelier and Robin. The resulting acceleration is determined by dividing this net force by the total mass of the system:\[ a = \frac{F_{net}}{m_{total}} \] In Robin's case, this gives us an acceleration of approximately \( 4.25 \text{ m/s}^2 \), meaning that's how quickly his speed increases as he is pulled upwards after the chandelier starts falling.
Tension in Ropes
Tension refers to the pulling force transmitted through a string, cable, or rope when it is pulled tight by forces acting from opposite ends. In this exercise, the tension in the rope is the key factor that ensures Robin is safely pulled upwards towards the balcony. The tension in the rope is influenced by both Robin's weight and the force needed to accelerate him upward. To find the tension, we calculate the force required to overcome his weight and add this to the force needed to produce the acceleration we already calculated:\[ T = m_{r}g + m_{r}a \]Here, \( m_{r}g \) is Robin's weight (the gravitational force acting on him), and \( m_{r}a \) is the force required to accelerate him upwards. Calculating these gives us a tension of approximately \( 1081.62 \text{ N} \). This tension ensures Robin is accelerated upwards effectively when the chandelier falls.

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