Which of the following pairs of spacetime events are separated by timelike, lightlike, and spacelike intervals? (these events are given by (ct, z, y,2) so you do not need to multiply the zeroth component by c). (a) (5,3,0,9) and (4,2,-1,8) (b) (8,6,7,5) and (10,7,8,6) (c) (2,3,6,0) and (0,3,7,0) (d) (-5,3,0,4) and (0,0,0,0) (e) (2,3,5,7) and (6,6,5,12)

Ablock of mass m slides on a horizontal frictionless table with an initial speed v0 . it then compresses a spring of force constant k and is brought to rest. the acceleration of gravity is 9.8 m/s2. how much is the spring compressed x from its natural length? 1) x = v0*sqrt(k/(mg)) 2) x=v0*sqrt(m/k) 3) x=v0*((mk)/g) 4) x=v0*sqrt(k/m) 5) x=v0*(m/kg) 6) x=v0*sqrt((mg)/k) 7) x=(v0)^2/(2g) 8) x=v0*(k/(mg)) 9) x=(v0)^2/(2m) 10) x=v0*((mg)/k)