A gas flows along the x axis with a speed of V = 5x m/s and a pressure of p = 10x2 N/m2, where x is in meters. (a) Determine the time rate of change of pressure at the fixed location x = 1. (b) Determine the time rate of change of pressure for a fluid particle flowing past x = 1. (c) Explain without using any equations why the answers to parts (a) and (b) are different

a)

b)

c) The answers to parts a) and b) are different because the rate of change of pressure is a function of position and in the two cases the position changes. In the later case the position is greater than 1 and the former case it is equal to 1.

Given:

expression of the speed of gas flow,

expression for the pressure of gas,

a)

Time rate of change of pressure at x=1:

............................(1)

now at point x=1

b)

From equation (1):

When x>1 then the rate of change in pressure:

c)

The answers to parts a) and b) are different because the rate of change of pressure is a function of position and in the two cases the position changes. In the later case the position is greater than 1 and the former case it is equal to 1.

f=ma a/f/m a= 480/60 a = 8m/s/s that is quick wow

the total distance traveled by the car is

30km + 49km = 79 km .