No sistema de corpos da figura a aceleração da gravidade vale 10 m/s², a massa a vale 4 kg e a massa b vale 6 kg. se o atrito entre o plano e a superfície de apoio é desprezível então a aceleração do conjunto é : a. 1 m/s² b. 4 m/s² c. 6 m/s² d. 0,25 m/s² e. 10 m/s²

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 ?

Find the momentum for a 2.6-kg brick parachuting straight downward at a constant speed of 8.4 m/s .

Aforce of 34n stretches a very light ideal spring 0.73 m from equilibrium, what is the force constant (spring constant) of the spring? (a) 47n/m (b) 38n/m (c) 53n/m (d) 25n/m