Math Problem Statement

Suppose you are climbing in the High Sierra when you suddenly find yourself at the edge of a fog-shrouded cliff. To find the height of this cliff, you drop a rock from the top and, 14.0s later, hear the sound of it hitting the ground at the foot of the cliff. Ignoring air resistance, how high is the cliff if the speed of sound is 330m/s?

Solution

To solve this problem, we need to break it into two parts:

  1. The time it takes for the rock to fall to the ground.
  2. The time it takes for the sound to travel back to the top of the cliff.

Step 1: Break down the total time

Let:

  • t1t_1 be the time it takes for the rock to fall.
  • t2t_2 be the time it takes for the sound to travel back up.

We know:

  • Total time, t1+t2=14.0t_1 + t_2 = 14.0 seconds.
  • The speed of sound is 330m/s330 \, \text{m/s}.

Step 2: Set up equations

For the rock falling:

We can use the equation of motion for free fall: h=12gt12h = \frac{1}{2} g t_1^2 Where:

  • hh is the height of the cliff.
  • g=9.8m/s2g = 9.8 \, \text{m/s}^2 (acceleration due to gravity).
  • t1t_1 is the time for the rock to fall.

For the sound:

The time for the sound to travel back up is: t2=h330t_2 = \frac{h}{330}

Step 3: Solve the system of equations

The total time is the sum of both times: t1+t2=14.0st_1 + t_2 = 14.0 \, \text{s} Substitute t2=h330t_2 = \frac{h}{330}: t1+h330=14.0t_1 + \frac{h}{330} = 14.0

Now, express hh in terms of t1t_1: h=12gt12=4.9t12h = \frac{1}{2} g t_1^2 = 4.9 t_1^2 Substitute this into the previous equation: t1+4.9t12330=14.0t_1 + \frac{4.9 t_1^2}{330} = 14.0 Now, let's solve this equation to find t1t_1.The valid solution for t1t_1 (time it takes the rock to fall) is approximately 11.90seconds11.90 \, \text{seconds} (we discard the negative value since time cannot be negative).

Step 4: Calculate the height of the cliff

Now that we have t1=11.90secondst_1 = 11.90 \, \text{seconds}, we can use the equation for the height of the cliff: h=4.9×t12h = 4.9 \times t_1^2 Let's compute hh.The height of the cliff is approximately 693.66meters693.66 \, \text{meters}.

Would you like further details or clarification?

Here are 5 related questions for further exploration:

  1. How would air resistance affect the time for the rock to fall?
  2. What would happen if the speed of sound was different, say on another planet?
  3. How does gravity influence the time it takes for an object to fall from a height?
  4. How could you estimate the speed of sound using this kind of experiment?
  5. How would the calculation change if the total time was measured inaccurately?

Tip: When solving problems involving motion and sound, always account for delays introduced by sound traveling at finite speeds!

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Math Problem Analysis

Mathematical Concepts

Kinematics
Free Fall
Speed of Sound

Formulas

h = 0.5 * g * t_1^2
t_2 = h / speed_of_sound
t_total = t_1 + t_2

Theorems

Newton's Laws of Motion

Suitable Grade Level

Grades 9-12