/*! 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 31 A wall clock has a second hand \... [FREE SOLUTION] | 91Ó°ÊÓ

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A wall clock has a second hand \(15.0 \mathrm{~cm}\) long. What is the radial acceleration of the tip of this hand?

Short Answer

Expert verified
The radial acceleration is approximately \(0.00246 \text{ m/s}^2\).

Step by step solution

01

Understand Radial Acceleration and Its Formula

Radial acceleration, also known as centripetal acceleration, is directed towards the center of the circular path. It is calculated using the formula \(a_r = \omega^2 r\), where \(\omega\) is the angular velocity and \(r\) is the radius of the circle.
02

Determine the Angular Velocity

The second hand of a clock makes one complete revolution in 60 seconds (1 minute). The angular velocity \(\omega\) is defined as: \[ \omega = \frac{2\pi}{T} \] where \(T\) is the period. Here, \(T = 60\, \text{seconds}\). Thus, \[ \omega = \frac{2\pi}{60} = \frac{\pi}{30} \text{ radians per second} \].
03

Use Radius to Find Radial Acceleration

The given length of the second hand is \(r = 15.0 \text{ cm} = 0.15 \text{ m}\). Plugging in the values into the radial acceleration formula:\[a_r = \omega^2 r = \left( \frac{\pi}{30} \right)^2 \times 0.15 \]\[a_r = \frac{\pi^2}{900} \times 0.15 \text{ m/s}^2\].
04

Calculate the Numerical Value

Calculate the value from Step 3:\[a_r = \frac{3.1416^2}{900} \times 0.15\]\[a_r \approx \frac{9.8696}{900} \times 0.15\]\[a_r \approx 0.00164 \times 0.15 \]\[a_r \approx 0.00246 \text{ m/s}^2 \].

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Key Concepts

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

Angular Velocity
In physics, angular velocity (\( \omega \)) is a measure of how quickly an object rotates around a circular path. It is the rate of change of the angle through which the object spins. For a rotating object such as the second hand of a clock, it completes a full circle in a set period. This completion of a circle can be quantified in radians, which is a standard unit of angular measurement.
  • A full circle is \( 2\pi \) radians.
  • The formula to calculate angular velocity is \( \omega = \frac{2\pi}{T} \), where \( T \) is the period or time taken to complete one full rotation.
For instance, the second hand completes its circle every 60 seconds, leading to an angular velocity of \( \frac{\pi}{30} \) radians per second, showing how quickly the hand moves around the clock face. Understanding angular velocity helps us determine how efficiently an object moves through circular paths.
Radial Acceleration
Radial acceleration, frequently referred to as centripetal acceleration, occurs when an object moves in a circular trajectory. It is always directed toward the center of the circular path and is crucial for ensuring the object continues moving in its circular course. Without it, the object would move off in a straight line due to inertia.
  • Radial acceleration is given by the formula \( a_r = \omega^2 r \), where \( \omega \) is the angular velocity and \( r \) is the radius.
  • This concept is integral in understanding circular motion dynamics.
For the second hand of the clock with a radius of 15 cm or 0.15 m, the radial acceleration can be calculated using its angular velocity, providing a result around 0.00246 \( \text{m/s}^2 \). This helps us see how centripetal force keeps the hand in its rotary motion.
Period of Rotation
The period of rotation (\( T \)) is the time it takes for an object to complete a single loop around a circular path. It is a critical factor in calculating angular velocity and radial acceleration. The shorter the period, the quicker the object makes its loop, impacting its speed and acceleration.
  • In the case of a clock's second hand, the period is consistent at 60 seconds, as each rotation takes exactly one minute.
  • Knowing the period helps ascertain how frequently an event (like a rotation) occurs within a specific timeframe.
Understanding the period is fundamental to grasping ideas like frequency and rhythm in rotary systems, offering insight into how often repetitive motions happen. This understanding aids in practical applications like mechanical design and time measurement.
Angular Motion
Angular motion describes the movement of an object along a circular path, involving both angular velocity and radial acceleration. This type of motion is prevalent in various situations, from the ticking of a clock to the rotating blades of a fan.
  • Angular motion combines rotational dynamics and kinematics principles.
  • It involves changes in an object's angular position and orientation over time.
The motion encompasses how objects travel around fixed points or revolve around axes. Grasping angular motion requires understanding complex interactions between speed, acceleration, and distance in circumnavigating loops. It allows us to model and predict behaviors in systems with rotating parts, essential in fields like engineering and physics.

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Most popular questions from this chapter

You swing a \(2.2 \mathrm{~kg}\) stone in a circle of radius \(75 \mathrm{~cm}\). At what speed should you swing it so its centripetal acceleration will be \(9.8 \mathrm{~m} / \mathrm{s}^{2} ?\)

Crossing the river, I. A river flows due south with a speed of \(2.0 \mathrm{~m} / \mathrm{s} .\) A man steers a motorboat across the river; his velocity relative to the water is \(4.2 \mathrm{~m} / \mathrm{s}\) due east. The river is \(800 \mathrm{~m}\) wide. (a) What is his velocity (magnitude and direction) relative to the earth? (b) How much time is required for the man to cross the river? (c) How far south of his starting point will he reach the opposite bank?

A pool ball is rolling along a table with a constant velocity. The components of its velocity vector are \(v_{x}=0.5 \mathrm{~m} / \mathrm{s}\) and \(v_{y}=0.8 \mathrm{~m} / \mathrm{s} .\) Calculate the distance it travels in \(0.4 \mathrm{~s}\).

A physics book slides off a horizontal tabletop with a speed of \(1.10 \mathrm{~m} / \mathrm{s} .\) It strikes the floor in \(0.350 \mathrm{~s}\). Ignore air resistance. Find (a) the height of the tabletop above the floor, (b) the horizontal distance from the edge of the table to the point where the book strikes the floor, and (c) the horizontal and vertical components of the book's velocity, and the magnitude and direction of its velocity, just before the book reaches the floor.

According to the Guinness Book of World Records, the longest home run ever measured was hit by Roy "Dizzy" Carlyle in a minor league game. The ball traveled 188 \(\mathrm{m}(618 \mathrm{ft})\) before landing on the ground outside the ballpark. (a) Assuming that the ball's initial velocity was \(45^{\circ}\) above the horizontal, and ignoring air resistance, what did the initial speed of the ball need to be to produce such a home run if the ball was hit at a point \(0.9 \mathrm{~m}(3.0 \mathrm{ft})\) above ground level? Assume that the ground was perfectly flat. (b) How far would the ball be above a fence \(3.0 \mathrm{~m}(10 \mathrm{ft})\) in height if the fence were \(116 \mathrm{~m}(380 \mathrm{ft})\) from home plate?

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