Which of the following actions could a person do to show how heat moves through conduction? А
A camper melts some marshmallows by holding them over a campfire.
B
A person uses an electric blanket to warm up on a cold evening.
с
A chef waits as pasta noodles rise and fall in a pot of boiling water.
D
A farmer heats up a metal rod to use as a brand by placing it into a fire.

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 ?

It is really hard for me right know

Atorque acting on an object tends to produce a. equilibrium b. rotation c. linear motion d. velocity e. a center of gravity