An object falls freely in a straight line and experiences air resistance proportional to its speed; this means its acceleration is a(t)equals minuskv(t), where k is a positive constant and v is the object's velocity. the speed of the object decreases from 1100 ft divided by s to 1000 ft divided by s over a distance of 1300 ft . approximate the time required for this deceleration to occur. hint: note that a(t)equals v prime (t ) and v(t)equals x prime (t ).
the time required for this deceleration to occur is approximately seconds. (do not round until the final answer. then round to four decimal places as needed.)

Athin plate moves between two parallel, horizontal, stationary flat surfaces at a constant velocity of v = 7.5 m/s. the two stationary surfaces are spaced 4 cm apart, and the medium between them is filled with oil whose viscosity is 0.9 n·s/m2. the part of the plate immersed in oil at any given time is 2 m long and 0.5 m wide. if the plate moves through the mid-plane between the surfaces, determine the force required to maintain this motion. what would your response be if the plate was 1 cm from the bottom surface (h2) and 3 cm from the top surface (h1)? if the plate moves through the mid-plane between the surfaces, the force required to maintain the motion will be n. if the plate was 1 cm from the bottom surface (h2) and 3 cm from the top (h1) surface, the force required to maintain the motion would be n.

Which articulations allow for greatest range of motion?

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.