# Poisson, Eric 's An advanced course in general relativity PDF

By Poisson, Eric

Similar physics books

Sample text

Finally, a new vector is constructed whose tail coincides with f( a, Fig. 3 . 3 Fig. 4 the tail of the first vector and whose head coincides with the head of the last vector (Fig. 3 . 3) . This closing side of the polygon is the resultant vector b, which is the sum being sought . Thus b = 8 1 + 8 2 + 83 + 8 4 + 85 This can be proved b y placing two vectors , 81 and 8 2 , in the xy-plane with the tail of vector a 2 at the head of vector 81 (Fig. 4) . Fig. 3 . 5 J oining the tail o f 8 1 with the head o f 8 2 , w e obtain vector b.

5 . 1 ) . The fundamental law of dynamics (otherwise called Newton's second law of motion) expresses the relation between force and the change in velocity of interacting bodies. The simplest form of the fund amental law of mechanics is valid for inertial reference frames . Noninerti al frames will be d ealt with further on (see Ch . 24) .

Suppose a particle has the instantaneous velocity v1 at the instant of time t1 and velocity v 2 at time t 2 • Then , accord ing to the definition , (4 . 1 ) The definition obviously implies that accelerati on is a vector . The direction of the acceleration vector depends upon the character of motion of the particle . This will be dealt with in more detail below. The instantaneous acceleration is a physical qu antity equal to the limit which the average acceleration approaches in an infinitely short time interval.