200 Puzzling Physics Problems: With Hints and Solutions potx

200 Puzzling Physics Problems... The Pitt Building, Trumpington Street, Cambridge, United KingdomCAMBRIDGE UNIVERSITY PRESS The Edinburgh Building, Cambridge CB2 2RU, UK 40 West 20th Str

200 Puzzling Physics Problems

The Pitt Building, Trumpington Street, Cambridge, United Kingdom

CAMBRIDGE UNIVERSITY PRESS

The Edinburgh Building, Cambridge CB2 2RU, UK

40 West 20th Street, New York, NY 10011-4211, USA

477 Williamstown Road, Port Melbourne, VIC 3207, Australia

Ruiz de Alarcon 13, 28014 Madrid, Spain Dock House, The Waterfront, Cape Town 8001, South Africa

http://www.cambridge.org

© Cambridge University Press 2001 This book is in copyright Subject to statutory exception

and to the provisions of relevant collective licensing agreements,

no reproduction of any part may take place without the written permission of Cambridge University Press

First published 2001 Reprinted 2002, 2003

Printed in the United Kingdom at the University Press, Cambridge

Typeface Monotype Times 10/13 pt System~TEX [UPH]

A catalogue record for this book is available from the British Library

Library0.(Congress Cataloguing in Publication data

1 Physics-Problems, exercises, etc I Title: Two hundred puzzling physics problems.

II Honyek, G (Gyula), 1951- III Riley, K F (Kenneth Franklin), 1936- IV Title.

QC32.G52 2001 530'.076-dc21 00-053005 CIP

ISBN 0 521 77306 7 hardback ISBN 0 521 77480 2 paperback

Preface

How to use this book

Thematic order of the problems

Xl

xiii

15069

In our experience, an understanding of the laws of physics is best acquired

by applying them to practical problems Frequently, however, the problemsappearing in textbooks can be solved only through long, complex calcu-lations, which tend to be mechanical and boring, and often drudgery forstudents Sometimes, even the best of these students, the ones who possessall the necessary skills, may feel that such problems are not attractive enough

to them, and the tedious calculations involved do not allow their 'creativity'(genius?) to shine through

This little book aims to demonstrate that not all physics problems are likethat, and we hope that you will be intrigued by questions such as:

• How is the length of the day related to the side of the road on whichtraffic travels?

• Why are Fosbury floppers more successful than Western rollers?

• How far below ground must the water cavity that feeds Old Faithfulbe?

• How high could the tallest mountain on Mars be?

• What is the shape of the water bell in an ornamental fountain?

• How does the way a pencil falls when stood on its point dependupon friction?

• Would a motionless string reaching into the sky be evidence forUFOs?

• How does a positron move when dropped in a Faraday cage?

• What would be the high-jump record on the Moon?

• Why are nocturnal insects fatally attracted to light sources?

• How much brighter is sunlight than moonlight?

• How quickly does a fire hose unroll?

VB