Name ______

Chapter19Test Review: Fluids & Flight

Define the following terms. Use formulas and state units where possible.

A Fluid / Any material that flows and offers little resistance to changing its shape. Examples are liquids & gases
Archimedes Principle / An object is buoyed up by a force equal to the weight of the fluid it displaces
Pascal’s Principle / Pascal’s principle says that the force exerted by a fluid on the walls of its container always acts perpendicular to the walls
and pushes from all sides. Additionally, pressure on a fluid is transmitted unchanged throughout the fluid.
Bernoulli’s Principle / The pressure in a fluid decreases as the speed of the fluid increases. It is based on the law of conservation of energy:
½ mv2+ pV + mgh =constant (KE + work + PE = const.)
Buoyancy & buoyant force / Buoyancy is an apparent weight loss of an object when submerged in a liquid. Buoyant force Fbuoy = ρVg
Where: ρ = density of the fluid & V = volume of the object
Apparent weight / FA: The difference between its actual weight and the buoyant force is the apparent weight: FA = w – FB
  1. What factors determine the pressure a fluid exerts on the bottom of its container?

Pressure of a liquid depends only on density (ρ), depth (h) and the gravitational acceleration (g). The pressure of a liquid is the same at any depth regardless of the shape of its container. P = ρgh

  1. What are the three types of heat transferred that were used in the hot air balloon lab (include examples)?

Convection: the balloon rose up because the hot air inside the balloon was surrounded by the cooler air of the room.

Conduction: the stovepipe that we used to fill the hot air balloon became hot from contact with the torches

Radiation: You could feel the heat from the torches while standing next to the balloon filling up.

  1. Calculate the buoyant force on a 60.0 kg raft with a volume of 15.0 m3floating in fresh water (density = 1,000 kg/m3)?

FB = ρVg = (1,000 kg/m3)(15.0 m3)(10 m/s2) = 150,000 N

  1. What is the weight of the raft?

Weight  F = ma = (60.0 kg)(10 m/s2) = 600 N

  1. What is the apparent weight of the raft? Will the raft float or sink? Explain your answer.

FA = w – FB = 600 N – 150,000 N = -149,400 N

The raft will float (explanation1) the buoyant force is greater than the weight of the raft, or (explanation2) the apparent weight is a negative value indicating that the net force is in the opposite direction of the gravitational force.

  1. Classify the following lab activities done in class as to what principle they explored; Archimedes, Pascal or Bernoulli’s
  1. ___Archemedes__ Determining the buoyant force on the Cartesian diver.
  2. _____Pascal______Getting the Cartesian diver to move up and down.