Physics Exam 2- Concepts for Chp. 10

equal to his weight

A sky diver falls through the air at terminal velocity. The force of air resistance on him is

48 m/s

An ideal fluid at 12 m/s in a horizontal pipe. If the pipe narrows to half its original radius, what is the flow speed in the narrower section?

3.0 m/s

An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its original radius, what is the flow speed in the wider section?

decreases

As the speed of a moving fluid increases, the pressure in the fluid

8.0W

Certain insects, such as the water bug are sufficiently lightweight that they can run on top of water without breaking the surface tension. Water bug A has weight W. Water bug B is twice as big as bug A, in all dimensions. That is, bug B is twice as long, twice as wide. What is the weight of bug B?

4.0F

Certain insects, such as the water bug, are sufficiently lightweight that they can run on top of water without breaking the surface tension. This is possible because the water, due to surface tension, exerts an upward force on the bottom of the bug's feet. Suppose that the maximum possible upward force on the feet of water bug A is F. Now suppose that water bug B is twice as big as bug A in every dimension. That is bug B is twice as long, twice as wide. What is the maximum upward force on the feet of bug B?

16Q

Two horizontal pipes are the same length, but pipe B has twice the diameter of pipe A. Water undergoes viscious flow in both pipes, subject to the same pressure difference across the lengths of the pipes. If the flow rate in pipe A is Q, what is the flow rate in pipe B?

2Q

Two horizontal pipes have the same diameter, but pipe B is twice as long as pipe A. Water undergoes viscous flow in both pipes, subject to the same pressure difference across the lengths of the pipes. If the flow rate in pipe B is Q what is the flow rate in pipe A?

the larger one

Two styrofoam balls, of radii R and 2R are released simultaneously from a tall tower. Which will reach the ground first?

Point A

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the speed of the water the greatest?

point B

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the water pressure greatest?

Where the velocity of fluid is high, the pressure is low; and where the velocity is low, the pressure is high

What is Bernoulli's principle?

4.0v

When a small spherical rock of radius r falls through water, its experiences a drag force arv, where "v" is its velocity and "a" is a constant proportional to the viscosity of water. From this, one can deduce that if a rock of diameter 2.0mm falls with terminal velocity "v", then a rock of diameter 4.0 mm will fall through with terminal velocity ___________

2h

When a tube of diameter d is placed in water, the water rises to a height h. If the diameter were half as great, how high would the water rise?

the increase in the surface tension of water with increasing temperature

When soup gets cold, it often tastes greasy. This greasy taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. To us "physikers", this is readily explained in terms of

the air above the paper moves faster and the pressure is lower

When you blow some air above a paper strip, the paper rises. This is because

the radius of the pipe

Which has the greatest effect on the flow of fluid through a narrow pipe? That is, if you made a 10% change in each of the quantities below, which would cause the greatest change in the flow rate? the fluid viscosity the pressure difference the length of the pipe the radius of the pipe

Bernoulli's principle

Which one of the following is associated with the law of conservation of energy in fluids?