Skip to main content

Q: I heard that in space, if you don't have a rope attach you to the space ship, you will just float/fly away. Why does that happen? and what kind of force is it? Derek

Actually, while we're on the subject of gravity, let's consider the case in which the space ship is in orbit around the Earth. The Earth's gravity weakens as you go away from the center of the Earth, inversely proportional to the square of the distance. If an astronaut is separated from his spaceship by a tiny distance, then the acceleration due to gravity will be slightly different and they will follow slightly different orbits, drifting apart.

If the astronaut has an initial velocity with respect to his spaceship which points away from the center of the Earth, his new orbit around the Earth will be elliptical with almost the same period, but the radius will oscillate outwards and inwards and back again. But even a small change in the period of the astronaut's orbit will take him far away from his spaceship.

Forces arising from the different strengths of gravity from one place to another are called "tidal" forces, because it is the variation of the sun's and the moon's gravitational fields across the size of the Earth that cause the tides.

These gravitational effects are quite small compared to what velocities can be picked up just by the astronaut stepping away from the spacecraft with some velocity, or by tossing a wrench, say in one direction and recoiling in another.


Popular posts from this blog



In  this  configuration  the  input  is  applied  between the  base  and  the  collector and  the  output  is  taken  from  the  collector  and  the  emitter.  Here  the  collector  is common to both the input and the output circuits as shown in Fig.

  Common Collector Transistor Circuit

In  common  collector  configuration  the  input  current  is  the  base current  IB  and  the output current is the emitter current IE. The ratio of change in emitter current to the  change in the base current is called current amplification factor.

It is represented by


A test  circuit  for determining the  static characteristic  of an NPN transistor is shown in Fig. In this circuit the collector is common to both the input and the output circuits.   To   measure   the   base   and   the   emitter   currents,   milli   ammeters   are connected in series with the base and the emitter circuits. Voltmeters are connected   across the input an…

XII - Ch# 12 : Electrostatics :Solved Numericals

Solution Manual : Mathematical methods for physicists 5th edition Arfken and Weber

DJ VU Reader
Book Description Now in its 7th edition, Mathematical Methods for Physicists continues to provide all the mathematical methods that aspiring scientists and engineers are likely to encounter as students and beginning researchers. This bestselling text provides mathematical relations and their proofs essential to the study of physics and related fields. While retaining the key features of the 6th edition, the new edition provides a more careful balance of explanation, theory, and examples. Taking a problem-solving-skills approach to incorporating theorems with applications, the book's improved focus will help students succeed throughout their academic careers and well into their professions. Some notable enhancements include more refined and focused content in important topics, improved organization, updated notations, extensive explanations and intuitive exercise sets, a wider range of problem solutions, improvement in the placement, and a wider ra…