/*! 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 33 A spring with \(k=170 \mathrm{~N... [FREE SOLUTION] | 91Ó°ÊÓ

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A spring with \(k=170 \mathrm{~N} / \mathrm{m}\) is at the top of a frictionless incline of angle \(\theta=37.0^{\circ}\). The lower end of the incline is distance \(D=1.00 \mathrm{~m}\) from the end of the spring, which is at its relaxed length. A \(2.00 \mathrm{~kg}\) canister is pushed against the spring until the spring is compressed \(0.200 \mathrm{~m}\) and released from rest. (a) What is the speed of the canister at the instant the spring returns to its relaxed length (which is when the canister loses contact with the spring)? (b) What is the speed of the canister when it reaches the lower end of the incline?

Short Answer

Expert verified
(a) Speed at spring relaxation: 1.84 m/s. (b) Speed at lower end: 3.90 m/s.

Step by step solution

01

Determine Initial Potential Energy of the Spring

The potential energy stored in a compressed or stretched spring is given by the formula:\[ U = \frac{1}{2} k x^2 \]where \( k \) is the spring constant, and \( x \) is the compression or extension.Here, \( k = 170 \; \mathrm{N/m} \) and \( x = 0.200 \; \mathrm{m} \).Substituting the values:\[ U = \frac{1}{2} \times 170 \times (0.200)^2 = 3.4 \; \mathrm{J} \]The potential energy stored in the spring is 3.4 J.
02

Use Conservation of Energy to find the Speed of the Canister when Spring is Relaxed

When the spring returns to its relaxed length, the potential energy converts into kinetic energy. At this point, there is no potential energy.By the conservation of energy:\[ \text{Initial Spring potential energy} = \text{Kinetic energy at relaxed length} \]\[ 3.4 = \frac{1}{2} m v^2 \]where \( m = 2.00 \; \mathrm{kg} \) and \( v \) is the speed to be determined.Re-arranging the equation for \( v \), we have:\[ v = \sqrt{\frac{2 \times 3.4}{2.00}} = \sqrt{3.4} \approx 1.84 \; \mathrm{m/s} \]The speed of the canister when the spring returns to its relaxed length is approximately 1.84 m/s.
03

Calculate the Additional Speed Using Gravity on the Incline

Now, consider the motion down the incline after the spring has relaxed completely. The gravitational potential energy loss converts to kinetic energy as the canister moves down the incline.The height \( h \) climbed/descended on the incline:\[ h = D \cdot \sin(\theta) = 1.00 \cdot \sin(37.0^{\circ}) \]Use \( \sin(37.0^{\circ}) \approx 0.602 \)\[ h = 1.00 \cdot 0.602 = 0.602 \; \mathrm{m} \]Gravitational potential energy loss:\[ \Delta U = mgh = 2.00 \cdot 9.8 \cdot 0.602 \approx 11.8 \; \mathrm{J} \]This energy also becomes kinetic energy:\[ \Delta U = \frac{1}{2} mv_{\text{bottom}}^2 - \frac{1}{2} mv_{\text{relaxed}}^2 \]Substitute the known values:\[ 11.8 = \frac{1}{2} \times 2.00 \times v_{\text{bottom}}^2 - 3.4 \]\[ v_{\text{bottom}}^2 = \frac{11.8 + 3.4}{1} = 15.2 \]\[ v_{\text{bottom}} = \sqrt{15.2} \approx 3.90 \; \mathrm{m/s} \]The speed of the canister at the lower end of the incline is approximately 3.90 m/s.

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Key Concepts

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

Spring Potential Energy
Spring Potential Energy is a type of stored energy that occurs when a spring is either compressed or extended. This energy can be calculated using the formula: \[ U = \frac{1}{2} k x^2 \]where:
  • \( U \) is the spring potential energy,
  • \( k \) is the spring constant (a measure of the stiffness of the spring),
  • \( x \) is the displacement from the spring's relaxed position.
In the exercise, the spring has a constant \( k = 170 \ \text{N/m} \) and is compressed by \( x = 0.200 \ \text{m} \). By substituting these values into the formula, the potential energy stored in the spring when compressed is calculated to be 3.4 joules. This energy is ready to be converted into kinetic energy when the spring returns to its relaxed state, propelling the canister forward.
Inclined Plane
An inclined plane is a flat surface tilted at an angle, which helps in moving objects upwards or downwards with less effort compared to lifting them directly. The angle of the incline is \( \theta \) (in this case, \(37.0^{\circ}\)).When dealing with inclined planes, it is important to calculate the component of gravitational force acting along the plane. This can be done using the sine of the angle of inclination. In this problem, the canister moves down an incline, converting its gravitational potential energy into kinetic energy. The height of descent along the incline is calculated as \( h = D \cdot \sin(\theta) \), where \( D \) is the distance along the incline. As a result, the canister gains speed due to the gravitational force pulling it down the slope.
Kinetic Energy
Kinetic Energy refers to the energy that a body possesses due to its motion. It can be calculated using the formula: \[ KE = \frac{1}{2} mv^2 \]where:
  • \( KE \) is the kinetic energy,
  • \( m \) is the mass of the object,
  • \( v \) is the velocity of the object.
In the spring and inclined plane problem, when the spring relaxes and releases its stored potential energy, this energy is converted to kinetic energy to give the canister its initial velocity. The exercise calculates this velocity when the spring is relaxed as approximately 1.84 m/s. Furthermore, as the canister descends the incline, additional gravitational energy is converted into kinetic energy, resulting in a higher speed at the bottom.
Gravitational Potential Energy
Gravitational Potential Energy is the energy an object possesses due to its position in a gravitational field. It can be described using the formula: \[ U_g = mgh \]where:
  • \( U_g \) is the gravitational potential energy,
  • \( m \) is the object’s mass,
  • \( g \) is the acceleration due to gravity, typically \(9.8 \ \text{m/s}^2\),
  • \( h \) is the height above the reference point.
In the context of the inclined plane, as the canister moves downward, it loses gravitational potential energy, which is converted into kinetic energy. This results in an increase in the speed of the canister as it reaches the bottom of the incline. The total gravitational potential energy lost by the canister in this setup is calculated to be approximately 11.8 joules, further augmenting its speed as it travels down the incline.

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Most popular questions from this chapter

A \(0.50 \mathrm{~kg}\) banana is thrown directly upward with an initial speed of \(4.00 \mathrm{~m} / \mathrm{s}\) and reaches a maximum height of \(0.80 \mathrm{~m}\). What change does air drag cause in the mechanical energy of the banana-Earth system during the ascent?

A block with mass \(m=2.00 \mathrm{~kg}\) is placed against a spring on a frictionless incline with angle \(\theta=30.0^{\circ}\) (Fig. 8-42). (The block is not attached to the spring.) The spring, with spring constant \(k=19.6 \mathrm{~N} / \mathrm{cm}\), is compressed \(20.0 \mathrm{~cm}\) and then released. (a) What is the elastic potential energy of the compressed spring? (b) What is the change in the gravitational potential energy of the block- Earth system as the block moves from the release point to its highest point on the incline? (c) How far along the incline is the highest point from the release point?

A block is sent sliding down a frictionless ramp. Its speeds at points \(A\) and \(B\) are \(2.00 \mathrm{~m} / \mathrm{s}\) and \(2.60 \mathrm{~m} / \mathrm{s}\), respectively. Next, it is again sent sliding down the ramp, but this time its speed at point \(A\) is \(4.00 \mathrm{~m} / \mathrm{s}\). What then is its speed at point \(B ?\)

A factory worker accidentally releases a \(180 \mathrm{~kg}\) crate that was being held at rest at the top of a ramp that is \(3.7 \mathrm{~m}\) long and inclined at \(39^{\circ}\) to the horizontal. The coefficient of kinetic friction between the crate and the ramp, and between the crate and the horizontal factory floor, is \(0.28 .\) (a) How fast is the crate moving as it reaches the bottom of the ramp? (b) How far will it subsequently slide across the floor? (Assume that the crate's kinetic energy does not change as it moves from the ramp onto the floor.) (c) Do the answers to (a) and (b) increase, decrease, or remain the same if we halve the mass of the crate?

A \(15 \mathrm{~kg}\) block is accelerated at \(2.0 \mathrm{~m} / \mathrm{s}^{2}\) along a horizontal frictionless surface, with the speed increasing from \(10 \mathrm{~m} / \mathrm{s}\) to 30 \(\mathrm{m} / \mathrm{s}\). What are (a) the change in the block's mechanical energy and (b) the average rate at which energy is transferred to the block? What is the instantaneous rate of that transfer when the block's speed is (c) \(10 \mathrm{~m} / \mathrm{s}\) and \((\mathrm{d}) 30 \mathrm{~m} / \mathrm{s} ?\)

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