An electret is similar to a magnet, but rather than being permanently magnetized, it has a permanent electric dipole moment. suppose a small electret with electric dipole moment 1.0 × 10−7 cm is 25 cm from a small ball charged to + 80 nc, with the ball on the axis of the electric dipole. what is the magnitude of the electric force on the ball?

Space-time metric ds2= -dt2+at2dx2+bt2dy2+ct2dz2 (a)how does the area of a rectangle with vertices at ( x=0, y=0, z=0 ), (1,0,0 ), ( 0,1,0 ) and (1,1,0 ) changes with time? (b) if a photon moving in the x direction starts from the origin at t=1, when does it reach x=l? (ds=0 for the trajectory of a photon.) (c) the proper time for a particle is defined by cd=ds. what is the proper time for a particle to move along the trajectory ( x(t)=t, y(t)=0, z(t)=0 ) from t=0 to 1 ? what is the condition on the parameter a so that the velocity of the particle never exceeds the speed of light ?

The image shows the positions of a car on a roller coaster track. arrange the cars in order based on their gravitational potential energy. begin with the lowest potential energy and end with the highest.

Most short-period comets do not have randomly oriented orbits because