What is meant by saying that a wave has a low frequency?

a. the wave is very tall
b. the wave is very long
c. few wave peaks pass a point in one second
d. a large number of wave peaks pass a point in one second.

In a wind tunnel the speed changes as the cross sectional area of the tunnel changes. if the speed in a 6' x 6' square test section is 100 mph, what was the speed upstream of the test section where the tunnel measured 20' x 20'? use conservation of mass and assume incompressible flow. conservation of mass requires that as the flow moves through a path or a duct the product of the density, velocity and cross sectional area must remain constant; i.e., that ova-constant. a model is being tested in a wind tunnel at a speed of 100 mph if the flow in the test section is at sea level standard conditions, what is the pressure at the model's stagnation point? (a) the tunnel speed is being measured by a pitot-static tube connected to a u- tube manometer. what is the reading on that manometer in inches of water? (b) at one point on the model a pressure of 2058 psf is measured. what is the local airspeed at that point?

Truck traveling west on the highway experiences an acceleration to the east. what could be the cause of this acceleration

Ais not a compound machine. a. bolt b. shovel c. handcart (dolly) d. see-saw (teeter totter)