/*! 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 42 You're an engineer designing kit... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

You're an engineer designing kitchen appliances, and you're working on a two- speed food blender, with 3600 rpm and 1800 rpm settings. Specs call for the blender to make no more than 60 revolutions while it's switching from high to low speed. If it takes \(1.4 \mathrm{s}\) to make the transition, does it meet its specs?

Short Answer

Expert verified
No, the blender does not meet its specs because it makes 63 revolutions during the switch, which is more than the allowed maximum of 60 revolutions.

Step by step solution

01

Convert the revolutions per minute into revolutions per second

Revolutions per minute can be converted into revolutions per second by dividing by 60. Therefore, the initial speed in revolutions per second is \(3600 \mathrm{rpm} / 60 = 60 \mathrm{rps}\). The final speed is \(1800 \mathrm{rpm} / 60 = 30 \mathrm{rps}\).
02

Find the average speed

The average speed during the transition (assuming uniform deceleration) is the average of the initial and final speeds. This can be obtained as \((60 \mathrm{rps} + 30 \mathrm{rps}) / 2 = 45 \mathrm{rps}\).
03

Calculate the number of revolutions during the transition period

Given that the time for the transition is 1.4 seconds, the average speed calculation can be utilized to ascertain the number of revolutions: \(45 \mathrm{rps} * 1.4 \mathrm{s} = 63 \mathrm{revolutions}\).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Angular Velocity
Angular velocity is a measure of how quickly an object rotates or revolves relative to another point. It's commonly used in physics to describe the rotation speed of an object, such as the blades of a blender. When we say that the angular velocity is 3600 revolutions per minute (rpm) for a blender, we're describing how many complete turns the blades make in one minute.

Understanding angular velocity involves not just the speed, but also the direction of rotation. For circular motion, it's usually measured in radians per second, but for practical applications like kitchen appliances, rpm is a more familiar term for most people.

As part of the problem at hand, knowing the initial and final angular velocities allows us to compute additional information about the blender's function, such as the number of revolutions made during a specific transition time.
Uniform Deceleration
Uniform deceleration occurs when an object slows down at a constant rate. This concept is critical when we consider the change in speed of an object, like the blades of a food blender moving from a higher to a lower setting. In our scenario, the blender shifts from 3600 rpm to 1800 rpm uniformly, meaning it loses speed at a steady rate.

Understanding uniform deceleration is important, as it simplifies many physics problems. With a constant deceleration, we can easily calculate average speeds and the distance—or in this case, the number of revolutions—traveled during the deceleration period. However, if the deceleration is not uniform, these computations become much more complex, involving calculus and more advanced kinematic equations.
Revolutions Per Minute
Revolutions per minute, or rpm, is a unit of rotational speed or angular velocity. It tells us how many times an object revolves around its axis in one minute. This measure is particularly useful in the context of rotating machines and devices, such as fans, engines, and yes, kitchen blenders.

To analyze problems in physics, we often convert rpm into more standard units like radians per second, because most equations utilize these standard units. However, in everyday applications and industry specifications, rpm is commonly used since it is much easier for people to visualize.

In the blender's example, we were given initial and final speeds in rpm, which we used to determine the average speed and calculate whether the transition between speeds meets the appliance's specifications. The conversion from rpm to revolutions per second (rps) is a simple but crucial step in problem-solving.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

You're an astronaut in the first crew of a new space station. The station is shaped like a wheel 22 m in diameter, with essentially all its \(5 \times 10^{5}-\mathrm{kg}\) mass at the rim. When the crew arrives, it will be set rotating at a rate that requires an object at the rim to have radial acceleration \(g\), thereby simulating Earth's surface gravity. This will be accomplished using two small rockets, each with \(100-\mathrm{N}\) thrust, mounted on the station's rim. Your job is to determine how long to fire the rockets and the number of revolutions the station will make during the firing.

A merry-go-round starts from rest and accelerates with angular acceleration \(0.010 \mathrm{rad} / \mathrm{s}^{2}\) for \(14 \mathrm{s}\). (a) How many revolutions does it make during this time? (b) What's its average angular speed?

A thin rod of length \(L\) and mass \(M\) is free to pivot about one end. If it makes an angle \(\theta\) with the horizontal, find the torque due to gravity about the pivot. (Hint: Integrate the torques on the mass elements composing the rod.)

You rev your car's engine and watch the tachometer climb steadily from 1200 rpm to 5500 rpm in 2.7 s. What are (a) the engine's angular acceleration and (b) the tangential acceleration of a point on the edge of the engine's 3.5 -cm-diameter crankshaft? (c) How many revolutions does the engine make during this time?

A \(320-\mathrm{N}\) frictional force acts on the rim of a 1.0 -m-diameter wheel to oppose its rotational motion. Find the torque about the wheel's central axis.

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.