Math Problem Statement

A 872 g block is released from rest at height h0 above a vertical spring with spring constant k = 460 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 23.1 cm. How much work is done (a) by the block on the spring and (b) by the spring on the block? (c) What is the value of h0? (d) If the block were released from height 3h0 above the spring, what would be the maximum compression of the spring?

Solution

This problem involves a block and a spring, and we need to calculate several things based on energy principles and spring mechanics. Here's a step-by-step solution:

Given:

  • Mass of block m=872g=0.872kgm = 872 \, \text{g} = 0.872 \, \text{kg}
  • Spring constant k=460N/mk = 460 \, \text{N/m}
  • Compression of spring x=23.1cm=0.231mx = 23.1 \, \text{cm} = 0.231 \, \text{m}

We'll tackle the problem part by part:

(a) How much work is done by the block on the spring?

The work done by the block on the spring is equivalent to the potential energy stored in the compressed spring. This is given by the formula:

Wblock=12kx2W_{\text{block}} = \frac{1}{2} k x^2

Substituting the values:

Wblock=12(460N/m)(0.231m)2W_{\text{block}} = \frac{1}{2} (460 \, \text{N/m}) (0.231 \, \text{m})^2 Wblock=12×460×0.053361W_{\text{block}} = \frac{1}{2} \times 460 \times 0.053361 Wblock=12.28JW_{\text{block}} = 12.28 \, \text{J}

(b) How much work is done by the spring on the block?

By Newton's third law, the work done by the spring on the block is the same in magnitude but opposite in direction as the work done by the block on the spring. Therefore:

Wspring=Wblock=12.28JW_{\text{spring}} = -W_{\text{block}} = -12.28 \, \text{J}

(c) What is the value of h0h_0?

To find the initial height h0h_0, we use the conservation of mechanical energy. Initially, the block has only gravitational potential energy, and when it compresses the spring, all this energy is converted into spring potential energy.

Using energy conservation:

mgh0=12kx2mgh_0 = \frac{1}{2} k x^2

Solving for h0h_0:

h0=12kx2mgh_0 = \frac{\frac{1}{2} k x^2}{mg}

Substituting the values:

h0=12×460×(0.231)20.872×9.81h_0 = \frac{\frac{1}{2} \times 460 \times (0.231)^2}{0.872 \times 9.81} h0=12.288.54832h_0 = \frac{12.28}{8.54832} h01.44mh_0 \approx 1.44 \, \text{m}

(d) What would be the maximum compression of the spring if the block were released from height 3h03h_0?

If the block is released from height 3h03h_0, it would have three times the gravitational potential energy. This energy would be converted into spring potential energy at maximum compression.

Using energy conservation again:

mg(3h0)=12kxmax2mg(3h_0) = \frac{1}{2} k x_{\text{max}}^2

We know h0h_0 from part (c), so:

mgh0=12kx2mgh_0 = \frac{1}{2} k x^2

Thus:

3mgh0=12kxmax23mgh_0 = \frac{1}{2} k x_{\text{max}}^2

Substituting h0=1.44mh_0 = 1.44 \, \text{m}:

3×0.872×9.81×1.44=12×460×xmax23 \times 0.872 \times 9.81 \times 1.44 = \frac{1}{2} \times 460 \times x_{\text{max}}^2

Simplifying:

36.88=230xmax236.88 = 230 x_{\text{max}}^2

Solving for xmaxx_{\text{max}}:

xmax2=36.88230=0.1603x_{\text{max}}^2 = \frac{36.88}{230} = 0.1603

xmax=0.16030.4mx_{\text{max}} = \sqrt{0.1603} \approx 0.4 \, \text{m}

Thus, the maximum compression of the spring is approximately 0.4 meters.


Would you like further clarification on any of these steps or details? Here are some related questions for further exploration:

  1. How would the work done change if the block's mass were doubled?
  2. What would happen to the spring compression if the spring constant were halved?
  3. How does the potential energy of the spring vary with the compression distance?
  4. What is the importance of energy conservation in spring-block systems?
  5. How would air resistance affect the energy conversions in this scenario?

Tip: Always ensure the units in your calculations are consistent, especially when dealing with different forms of energy (e.g., gravitational vs. spring potential energy).

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Math Problem Analysis

Mathematical Concepts

Energy Conservation
Work-Energy Principle
Spring Mechanics

Formulas

Work done by block: W_block = (1/2) k x^2
Conservation of mechanical energy: mgh0 = (1/2) k x^2
Work done by spring: W_spring = -W_block

Theorems

Newton's Third Law
Conservation of Energy

Suitable Grade Level

Grades 10-12