/*! 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 72 You are given the equation(s) us... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

You are given the equation(s) used to solve a problem. For each of these, you are toIn Problems 69 through 72 you are given the equation(s) used to solve a problem. For each of these, you are to a. Write a realistic problem for which this is the correct equation(s). b. Draw a pictorial representation. c. Finish the solution of the problem. $$\begin{array}{l}T-(1500 \mathrm{kg})\left(9.8 \mathrm{m} / \mathrm{s}^{2}\right)=(1500 \mathrm{kg})\left(1.0 \mathrm{m} / \mathrm{s}^{2}\right) \\ P=T(2.0 \mathrm{m} / \mathrm{s})\end{array}$$

Short Answer

Expert verified
The crane should exert a tension of 16200 N to lift the block at a constant speed of 1.0 m/s. The power required is 32.4 kW for the crane to work at a speed of 2.0 m/s.

Step by step solution

01

Formulate a Realistic Problem

To begin with, create a real world scenario with the given equations. For instance, imagine you have a construction crane that needs to lift a 1500 kg concrete block at a constant speed of 1.0 m/s against gravity (9.8 m/s²). We need to also know the power required for the crane to work at it's operation speed of 2.0 m/s.
02

Draw a Pictorial Representation

Draw a crane lifting a block vertically upwards in this step. Label the block's weight (1500 kg), the acceleration due to gravity (9.8 m/s² downwards), the block's upward acceleration (1.0 m/s²), and the crane's operational speed (2.0 m/s).
03

Solve for Tension

Begin by solving for the tension (T) in the rope using the first equation: \(T - (1500 kg * 9.8 m/s²) = 1500 kg * 1.0 m/s²\). First, calculate the weight of the block, which is mass times gravity: \(1500 kg * 9.8 m/s² = 14700 N\). Substitute this into the equation: \(T - 14700 N = 1500 N\). Rearrange the equation to solve for T: \(T = 14700 N + 1500 N = 16200 N\). Thus, the tension in the rope is 16200 N.
04

Solve for Power

Next, substitute T = 16200 N into the second equation to find power (P): \(P = T * 2.0 m/s = 16200 N * 2.0 m/s = 32400 W\). The power required for the crane to work at it's operation speed of 2.0 m/s is 32.4 kW.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Tension in Physics
Tension is a force exerted by a string, cable, or similar object that is pulling on another object. It's essential in understanding a variety of physics problems, particularly those involving forces in mechanical systems like cranes, elevators, or even bridges. The tension in a rope or chain is what allows these structures to move or support loads.

In the context of our textbook problem, tension represents the force exerted by the crane’s cable when lifting the 1500 kg concrete block vertically upwards against Earth’s gravity. It's not simply the weight of the block; it also includes any additional force required to accelerate the block upwards at 1.0 m/s².

To solve for tension in a vertical lift problem, you’ll want to use Newton's second law of motion: \( F = ma \) where \( F \) is the net force, \( m \) the mass, and \( a \) the acceleration of the object. Here, the acceleration includes both gravity and any other acceleration the object experiences. Tension is effectively the net force needed to overcome gravity and provide the additional acceleration. When calculating tension, it's important to account for all forces acting on the object, especially when it's not just hanging statically but is being accelerated.
Kinematics Equations
Kinematics equations are the backbone of motion problems in physics. They enable us to predict the future position, velocity, and acceleration of an object moving under a constant acceleration. These equations don't take into account the forces that cause the motion, which is where dynamics, including tension, comes into play.

While kinematics equations aren’t explicitly stated in the problem, understanding them can enhance the process of problem solving. For instance, if we knew the crane had to lift the block to a certain height in a given time, we could use kinematics equations to determine the required initial velocity and the time it would take to reach the target height.

More complex problems may require the combined use of kinematics and dynamics (involving tension) to find a solution. For a simple vertical lift at constant speed, the kinematics is straightforward: Velocity is constant, and acceleration is due to gravity, which we counteract to lift the block. However, if the speed changes, kinematics equations help us to understand how the velocity and position change over time, which in turn affects the tension in the system.
Power in Mechanical Systems
Power in mechanical systems is a measure of how quickly work is done or energy is transferred. It’s a crucial concept in any discussion about efficiency and the practicality of machinery, including cranes, cars, and electrical appliances. In physics, power (\( P \)) is calculated by multiplying the force applied (tension in the case of the crane) by the velocity of the object in the direction of the force: \( P = Fv \), where \( F \) is force and \( v \) is velocity.

In the textbook exercise, after finding the tension using Newton’s laws, we need to calculate the power the crane must deliver to lift the block at the operational speed of 2.0 m/s. The calculated power gives us an insight into the energy consumption and efficiency of the crane. It’s worth noting that power is not constant in all situations – it can change depending on the speed and force applied.

Knowing how to calculate power helps understand the limitations and capabilities of mechanical systems, and when designing real-life systems, it ensures they operate within safe and efficient parameters. The 32.4 kW of power required by the crane, as established in this problem, is a clear indication of the crane’s operational demands when it's lifting a heavy load.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Show that Hooke's law for an ideal spring is a conservative force. To do so, first calculate the work done by the spring as it expands from A to B. Then calculate the work done by the spring as it expands from A to point C, which is beyond B, then returns from C to B.

A particle of mass \(m\) starts from \(x_{0}=0\) m with \(v_{0}>0\) m/s. The particle experiences the variable force \(F_{x}=F_{0} \sin (c x)\) as it moves to the right along the \(x\) -axis, where \(F_{0}\) and \(c\) are constants. a. What are the units of \(F_{0} ?\) b. What are the units of \(c ?\) c. At what position \(x_{\max }\) does the force first reach a maximum value? Your answer will be in terms of the constants \(F_{0}\) and \(c\) and perhaps other numerical constants. d. Sketch a graph of \(F\) versus \(x\) from \(x_{0}\) to \(x_{\max }\) c. What is the particle's velocity as it reaches \(x_{\max } ?\) Give your answer in terms of \(m, v_{0}, F_{0},\) and \(c .\)

In a hydroelectric dam, water falls \(25 \mathrm{m}\) and then spins a turbine to generate electricity. a. What is \(\Delta U\) of \(1.0 \mathrm{kg}\) of water? b. Suppose the dam is \(80 \%\) efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines cach second to generate 50 MW of electricity? This is a typical value for a small hydroelectric dam.

Evaluate the dot product \(\overrightarrow{\boldsymbol{A}} \cdot \overrightarrow{\boldsymbol{B}}\) if a. \(\vec{A}=3 \hat{i}-4 \hat{j}\) and \(\vec{B}=-2 \hat{i}+6 \hat{j}\) b. \(\vec{A}=2 \hat{i}+3 \hat{j}\) and \(\vec{B}=6 \hat{i}-4 \hat{j}\)

A cable with \(20.0 \mathrm{N}\) of tension pulls straight up on a \(1.02 \mathrm{kg}\) block that is initially at rest. What is the block's speed after being lifted \(2.00 \mathrm{m} ?\) Solve this problem using work and energy.

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.