/*! 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} 2Q Question: A student said, "When ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Question: A student said, "When the Moon goes around the Earth, there is an inward force due to the Moon and an outward force due to centrifugal force, so the net force on the Moon is zero." Give two or more physics reasons why this is wrong.

Short Answer

Expert verified

Answer

The net force is non-zero.

Step by step solution

01

Definition of centrifugal force

In a circular motion, the centrifugal force works along the circle's radius and acts away from the circle's centre.

When measuring in an inertial frame of reference, the force does not exist. It only becomes relevant when switching from a ground/inertial to a spinning reference frame.

02

Calculation of the net force

The net force on an object can be expressed as the sum of two parts and it is equal to the rate of change of the momentum.

The two parts that we are taken about are the parallel rate of change of the momentum and the perpendicular rate of change of the momentum .

Write the net force on the object.

03

Analysis of the momentum

The moon experiences an inward gravitational attraction as it revolves around the Earth. Although there is an outward centrifugal force, it is not a true force. On equating them, the result will be a non-zero net force on the moon. As a result, the stated assertion is incorrect.

The object is moving in a curved path, and its momentum is constantly changing. Even if the object moves with constant speed, a change of direction indicates that dÓ¬pdtis non zero.

Hence, the net force is non zero.

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!

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

A sports car (and its occupants) of massis moving over the rounded top of a hill of radius RAt the instant when the car is at the very top of the hill, the car has a speed v. You can safely neglect air resistance.

(a) Taking the sports car as the system of interest, what object(s) exert non negligible forces on this system?

(b) At the instant when the car is at the very top of the hill, draw a diagram showing the system as a dot, with force vectors whose tails are at the location of the dot. Label the force vectors (that is, give them algebraic names). Try to make the lengths of the force vectors be proportional to the magnitudes of the forces.

(c) Starting from the Momentum Principle calculates the force exerted by the road on the car.

(d) Under what conditions will the force exerted by the road on the car be zero? Explain.

A child of mass 35kgsits on a wooden horse on a carousel. The wooden horse is 3.3mfrom the center of the carousel, which rotates at a constant rate and completes one revolution every 5.2s.

(a) What are the magnitude and direction (tangential in direction of velocity, tangential in the opposite direction of the velocity, radial outward, radial inward) of (dp→/dt)pÁåœ, the parallel component of dp→/dtfor the child?

(b) What are the magnitude and direction of \p→\dp/dt. the perpendicular component of dp→/dtfor the child?

(c) What are the magnitude and direction of the met force acting on the child? (d) What objects in the surroundings contribute to this horizontal net force acting on the child? (There are also vertical forces, but these cancel each other if the horse doesn't move up and down.)

A box of mass 40 kghangs motionless from two ropes, as shown in Figure. The angle is 38°. Choose the box as the system. The xaxis runs to the right, the yaxis runs up, and the zaxis is out of the page.

(a) Draw a free-body diagram for the box.

(b) Isdp→/dtof the box zero or nonzero?

(c) What is the ycomponent of the gravitational force acting on the block? (A component can be positive or negative).

(d) What is theycomponent of the force on the block due to rope 2?

(e) What is the magnitude of localid="1657085603204" F→2?

(f) What is thexcomponent of the force on the block due to rope 2?

(g) What is the xcomponent of the force on the block due to rope 1?

An engineer whose mass is 70kgholds onto the outer rim of a rotating space station whose radius is 14mand which takes 30sto make one complete rotation. What is the magnitude of the force the engineer has to exert in order to hold on? What is the magnitude of the net force acting on the engineer?

A block with mass 0.4 kgis connected by a spring of relaxed length 0.15 mto a post at the centre of a low-friction table. You pull the block straight away from the post and release it, and you observe that the period of oscillation is 0.6 s. Next you stretch the spring to a length of 0.28mand give the block an initial speed vperpendicular to the spring, choosing vso that the motion is a circle with the post at the centre. What is this speed?

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.