A model rocket is fired vertically upward from rest. Its acceleration for the first three seconds is a(t) = 66 t, at which time the fuel is exhausted and it becomes a freely "falling" body. 15 seconds later, the rocket's parachute opens, and the (downward) velocity slows linearly to -23 ft/s in 5 s. The rocket then "floats" to the ground at that rate.

Determine the position function s and the velocity function v (for all times t).

Aball with a mass of 275 g is dropped from rest, hits the floor and rebounds upward. if the ball hits the floor with a speed of 2.40 m/s and rebounds with a speed of 1.70 m/s, determine the following. (a) magnitude of the change in the ball's momentum (let up be in the positive direction.)

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0