Un automóvil que viaja a 56 km/hr está a 34 m de una barrera cuando el conductor
pisa de golpe los frenos. Cuatro segundos
más tarde el automóvil golpea la barrera. a)
¿Cuál fue la desaceleración constante del
automóvil antes del impacto. b) ¿A qué
velocidad viajaba el auto antes del
impacto?

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 ?

Around faucet handle is part of a(n) a. lever b. screw c. inclined plane d. wheel and axle

Assume similar data for the motion of the blood in your aorta. estimate how many beats of the heart it will take the blood to get from your heart to your brain. (assume that the distance from your heart to your brain is 30 cm)