/*! 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 20 Combining conservation laws. A 1... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Combining conservation laws. A 15.0 kg block is attached to a very light horizontal spring of force constant 500.0 \(\mathrm{N} / \mathrm{m}\) and is resting on a frictionless horizontal table. (See Figure \(8.38 .\) ) Suddenly it is struck by a 3.00 \(\mathrm{kg}\) stone traveling horizontally at 8.00 \(\mathrm{m} / \mathrm{s}\) to the right, whereupon the stone rebounds at 2.00 \(\mathrm{m} / \mathrm{s}\) horizontally to the left. Find the maximum distance that the block will compress the spring after the collision. (Hint: Break this problem into two parts the collision and the behavior after the collision \(-\) and apply the appropriate conservation law to each part.)

Short Answer

Expert verified
The maximum spring compression is approximately 0.346 m.

Step by step solution

01

Analyze the Collision Using Conservation of Momentum

First, we need to apply the conservation of momentum to the collision between the stone and the block. The total momentum before the collision is equal to the total momentum after the collision. The initial momentum is the momentum of the stone since the block is initially at rest. Therefore, we have:\[ m_1 v_{1i} + m_2 v_{2i} = m_1 v_{1f} + m_2 v_{2f} \]where \(m_1 = 3.00\, \mathrm{kg}\), \(v_{1i} = 8.00\, \mathrm{m/s}\), and \(v_{1f} = -2.00\, \mathrm{m/s}\) for the stone. The block is initially at rest, so \(v_{2i} = 0\). Substituting the known values gives:\[ 3.00\, \mathrm{kg} \times 8.00\, \mathrm{m/s} = 3.00\, \mathrm{kg} \times (-2.00\, \mathrm{m/s}) + 15.0\, \mathrm{kg} \times v_{2f} \]\[ 24.0 = -6.0 + 15.0 \times v_{2f} \]\[ 30.0 = 15.0 \times v_{2f} \]\[ v_{2f} = 2.00\, \mathrm{m/s} \]The speed of the block immediately after the collision is \(2.00\, \mathrm{m/s}\).
02

Apply Conservation of Energy to Determine Spring Compression

After the collision, the block moves with a speed of \(2.00\, \mathrm{m/s}\) and compresses the spring until it comes to a stop, entirely converting its kinetic energy to the potential energy stored in the spring. We apply conservation of energy:\[ \text{Initial kinetic energy of the block} = \text{Potential energy of the spring} \]\[ \frac{1}{2} m v^2 = \frac{1}{2} k x^2 \]where \(m = 15.0\, \mathrm{kg}\), \(v = 2.00\, \mathrm{m/s}\), \(k = 500.0\, \mathrm{N/m}\), and \(x\) is the maximum compression of the spring. Solving for \(x\):\[ \frac{1}{2} \times 15.0 \times (2.00)^2 = \frac{1}{2} \times 500.0 \times x^2 \]\[ 30.0 = 250.0 \times x^2 \]\[ x^2 = \frac{30.0}{250.0} \]\[ x^2 = 0.12 \]\[ x = \sqrt{0.12} \approx 0.346\, \mathrm{m} \]The maximum compression of the spring is approximately \(0.346\, \mathrm{m}\).

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.

Conservation of Energy
The concept of conservation of energy is crucial when analyzing how energy is transformed within a system. In this exercise, after the collision, the block moves with a certain kinetic energy. The key idea is that as the block compresses the spring, its kinetic energy is being transformed into potential energy stored in the spring.
Kinetic energy is expressed as \( \frac{1}{2} m v^2 \), where \(m\) is mass and \(v\) is velocity. Potential energy in a spring is given by \( \frac{1}{2} k x^2 \), where \(k\) is the spring constant and \(x\) is the displacement from the equilibrium position.
  • As the block comes to rest, all of its kinetic energy is converted to potential energy.
  • This is a closed system, so the sum of energy remains constant.
The transformation of energy types allows us to find the compression of the spring by equating the kinetic energy of the block to the potential energy of the compressed spring.
Spring Compression
Spring compression involves the displacement of the spring from its natural length due to an external force. When an object strikes a spring, the spring exerts an equal and opposite force as it compresses. This exercise shows that when a 15 kg block compresses a spring, it does so until all its kinetic energy is converted to potential energy.
The force constant \(k\) gives us measure of a spring's stiffness, higher the \(k\), stiffer is the spring. Maximum compression \(x\) can be calculated from the energy conservation equation: \[ \frac{1}{2} m v^2 = \frac{1}{2} k x^2 \]
The left side represents the energy due to motion and the right side represents energy stored in the spring. Solving for \(x\) provides the extent to which the spring compresses. Such problems help us understand the elasticity and energy storage potential of springs.
Collision Analysis
Collision analysis is all about looking into how objects interact during a collision and how momentum is preserved. Here, the collision is between a 3 kg stone and a 15 kg block, where momentum before and after the collision should remain constant, according to the conservation of momentum formula: \[ m_1 v_{1i} + m_2 v_{2i} = m_1 v_{1f} + m_2 v_{2f} \]
The left side of this equation represents initial total momentum before collision, while the right side shows total momentum after. Analyzing momentum gives insight into post-collision speeds of the involved objects.
  • The block's velocity after the interaction is calculated using the momentum conservation principle.
  • The stone's rebound speed helps determine the final velocity of the block.
Such analysis reveals that during the collision, while individual momentum of bodies change, the overall system’s momentum stays constant, giving a foundational understanding of momentum conservation principles.

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

BIO Momentum and the squirting squid. An interesting use of "rocket power" is that used by cephalopods such as octopi and squids. These animals take in seawater and then squirt it out at high speed. \(\mathrm{A} 2.5\) -kg squid can expel 0.25 \(\mathrm{kg}\) of seawater \((\mathrm{in}\) a short burst of 0.20 \(\mathrm{s} )\) with a speed of 600 \(\mathrm{cm} / \mathrm{s}\) What is the momentum of one squirt of water? $$\begin{array}{l}{\text { A. } 1.2 \mathrm{kg} \cdot \mathrm{m} / \mathrm{s} \text { in the direction of the squirt }} \\ {\text { B. } 1.5 \mathrm{kg} \cdot \mathrm{m} / \mathrm{s} \text { in the direction of the squirt }} \\\ {\text { C. } 12 \mathrm{kg} \cdot \mathrm{m} / \mathrm{s} \text { in the direction of the squirt }} \\ {\text { D. } 15 \mathrm{kg} \cdot \mathrm{m} / \mathrm{s} \text { in the direction of the squirt }}\end{array} $$

. Bone fracture. Experimental tests have shown that bone will rupture if it is subjected to a force density of \(1.0 \times\) \(10^{8} \mathrm{N} / \mathrm{m}^{2} .\) Suppose a 70.0 \(\mathrm{kg}\) person carelessly roller-skates into an overhead metal beam that hits his forehead and completely stops his forward motion. If the area of contact with the person's forehead is \(1.5 \mathrm{cm}^{2},\) what is the greatest speed with which he can hit the wall without breaking any bone if hiss head is in contact with the beam for 10.0 \(\mathrm{ms}\) ?

\(\bullet\) A ball with a mass of 0.600 \(\mathrm{kg}\) is initially at rest. It is struck by a second ball having a mass of 0.400 \(\mathrm{kg}\) , initially moving with a velocity of 0.250 \(\mathrm{m} / \mathrm{s}\) toward the right along the \(x\) axis. After the collision, the 0.400 \(\mathrm{kg}\) ball has a velocity of 0.200 \(\mathrm{m} / \mathrm{s}\) at an angle of \(36.9^{\circ}\) above the \(x\) axis in the first quadrant. Both balls move on a frictionless, horizontal surface. (a) What are the magnitude and direction of the velocity of the 0.600 kg ball after the collision? (b) What is the change in the total kinetic energy of the two balls as a result of the collision?

A rocket is fired in deep space, where gravity is negligible. If the rocket has an initial mass of 6000 \(\mathrm{kg}\) and ejects gas at a relative velocity of magnitude 2000 \(\mathrm{m} / \mathrm{s}\) , how much gas must it eject in the first second to have an initial acceleration of 25.0 \(\mathrm{m} / \mathrm{s}^{2}\) .

\(\cdot\) On a highly polished, essentially frictionless lunch counter, a 0.500 kg submarine sandwich moving 3.00 \(\mathrm{m} / \mathrm{s}\) to the left collides with a 0.250 \(\mathrm{kg}\) grilled cheese sandwich moving 1.20 \(\mathrm{m} / \mathrm{s}\) to the right. (a) If the two sandwiches stick together, what is their final velocity? (b) How much mechanical energy, dissipates in the collision? Where did this energy go?

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.