Part A A physics student solving a physics problem has obtained the following four equations that describe the physics of a system of
masses connected by a string
(1) mg 3m
(2) -mg cos 0+T - mai
(3) a-09
(4) mag-T-mga
where g 9.80 meter/second and 0 -60 are knowns, and my my, as, as, and T are unknowns. The problem requires
the student to evaluate as Which are the unknowns that the student would like to eliminare from the equations?

When the velocity of an object is doubled, by what factor is its momentum changed? by what factor is its kinetic energy changed? a) the momentum is zero. b) the momentum is not zero. c) difficult to say.

The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.0 × 10-6 c/m2. (a) what is the magnitude of the electric field within the cell membrane? (b) find the magnitude of the electric force that would be exerted on a potassium ion (k+; charge = +e) placed inside the membrane.

Una carga puntual de 3 x 10-6 c se coloca a 12 cm de una segunda carga puntual de - 1,5 x 10-6 c. calcular la magnitud fuerza eléctrica entre las cargas