What is Luis' displacement? (do not include the label "m" in your answer) * As shown in the figure below. Luis walks 40 m toward his truck. He notices he forgot his keys, so he
returns back to his house. His total travel time is 95 s.
40 m
40 m

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 ?

Where is the potential energy throughout the loading, cocking, and releasing of the trebuchet?

What is the coefficient of kinetic friction μk between the block and the tabletop?