The block in the drawing has dimensions l0×2l0×3l0,where l0 =0.5 m. the block has a thermal conductivity of 200 j/(s·m·c˚). in drawings a, b, and c, heat is conducted through the block in three different directions; in each case the temperature of the warmer surface is 37 ˚c and that of the cooler surface is 7 ˚c determine the heat that flows in 4 s for each case.

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 ?

Which of the following represents an upright image? a. -do b. +m c. -m d. +do

What is the rate of change in a objects position?