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Between 1911 and 1990 tower at Pisa, Italy, moved toward the south at an average rate of \(1.2 \mathrm{~mm} / \mathrm{y}\). The tower is \(55 \mathrm{~m}\) tall. In radians per second, what is the average angular speed of the tower's top about its base?

Short Answer

Expert verified
The average angular speed is approximately \(5.47 \times 10^{-13}\) radians per second.

Step by step solution

01

Calculate the total displacement

First, determine the total displacement of the tower from 1911 to 1990. This is calculated by multiplying the average rate of movement by the total number of years between these dates. The number of years from 1911 to 1990 is \(1990 - 1911 = 79\) years. Therefore, the total displacement is \(1.2 \mathrm{~mm/year} \times 79 \mathrm{~years} = 94.8\) mm.
02

Convert displacement to meters

Since the displacement should be in meters for easier calculations with the height, convert 94.8 mm to meters. There are 1000 mm in a meter, so divide by 1000: \(94.8 \mathrm{~mm} = 0.0948\) meters.
03

Calculate the angular displacement

The angular displacement \(\theta\) can be found by dividing the linear displacement by the radius of motion (height of the tower, which acts as the radius). Hence, \(\theta = \frac{0.0948 \mathrm{~m}}{55 \mathrm{~m}}\).
04

Calculate the angular speed

Angular speed \(\omega\) is the change in angular displacement over time. We calculated \(\theta\) for the total period (79 years), so \(\omega = \theta / \text{time in seconds}\). First, convert 79 years to seconds: \(79 \times 365 \times 24 \times 60 \times 60\). Then, calculate the speed: \(\omega = \frac{0.0948/55}{79 \times 365 \times 24 \times 60 \times 60}\) radians/second.

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Key Concepts

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

Angular Displacement
Angular displacement refers to how much an object rotates around a specific point or axis. For the Leaning Tower of Pisa, the angular displacement tells us how much the top of the tower has rotated around its base over a period of time. When we calculate angular displacement, we are looking at how changes in position translate into rotational movement.
For this exercise, we use the formula:\[theta = \frac{s}{r}\]
  • \(\theta\) represents the angular displacement in radians.
  • \(s\) is the linear displacement, in this case, the distance the top of the tower moved.
  • \(r\) is the radius or the height of the tower, which is the pivot point for our rotation.
By understanding angular displacement, students can visualize how a seemingly linear movement (like the top of a tower shifting slightly each year) can be expressed as rotational motion over time. This concept is crucial in various fields, including physics and engineering.
Linear Displacement
Linear displacement is a measure of the distance something travels in a straight line. This is different from angular displacement, which deals with rotation or angles. In the context of the Leaning Tower of Pisa, linear displacement is the distance that the top of the tower moves from its original position.
In the problem, we calculated linear displacement by determining the total distance the tower moved over 79 years, which was found to be 94.8 mm.
  • Linear displacement can often be expressed in units such as meters, millimeters, or inches.
  • This measurement helps us to understand the extent of motion in a straight path.
Linear displacement is essential in calculating angular displacement because it provides the initial data we need. By converting linear displacement into a form related to rotation (through division by the height of the tower), we were able to compute the tower's angular displacement.
Conversion of Units
A crucial aspect of solving physics problems is the conversion of units. Different situations require measurements in specific units for the calculations to make sense. In this problem, we first measure the tower’s movement in millimeters per year, but later convert this measurement into meters.
  • To convert millimeters to meters, divide by 1000 since there are 1000 millimeters in a meter.
  • For time, converting years into seconds involves multiplying by the number of days in a year, then hours in a day, followed by minutes in an hour, and finally by seconds in a minute.
This ensures all quantities are in compatible units, allowing us to accurately calculate angular speed. Mistakes in unit conversion can lead to erroneous answers, so it’s important to convert all relevant measurements before proceeding with calculations. This concept helps students refine their problem-solving skills across various scientific disciplines.
Average Rate of Movement
The average rate of movement describes how much an object’s position changes over a specific period of time. In this example, the top of the Leaning Tower of Pisa moved an average of 1.2 mm per year. This tells us about the tower’s gradual lean over many decades.
  • Knowing the average rate allows us to compute total displacement over a given time, which is crucial for determining angular displacement and speed.
  • This rate is constant, simplifying the process of calculating total movement over the 79-year period and serving as the basis for further calculations.
Understanding the concept of average rate of movement helps students comprehend how simple rates can predict and model long-term changes in position or motion. This concept forms the backbone of many practical applications in everyday life and scientific research.

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Most popular questions from this chapter

A flywheel with a diameter of \(1.20 \mathrm{~m}\) is rotating at an angular speed of 200 rev/min. (a) What is the angular speed of the flywheel in radians per second? (b) What is the linear speed of a point on the rim of the flywheel? (c) What constant angular acceleration (in revolutions per minute- squared) will increase the wheel's angular speed to 1000 rev/min in \(60.0 \mathrm{~s}\) ? (d) How many revolutions does the wheel make during that \(60.0 \mathrm{~s}\) ?

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