1. Chapter 3: Forces & Fluids Review

2. How can you change the pressure on the ground when you are standing?  Stand on one foot (decrease area)  Change into high heels (decrease area)  Decrease the space on which you are standing (decrease area)  Hold something with more mass (increase force)

3. Does 100 mL of soda exert the same amount of pressure in a 100 mL bottle as a 200 mL bottle?  No, the 100 mL of soda would exert more pressure in the 100 mL bottle because it has less area to exert its force.

4. Describe the buoyant force of an object that sinks.  The buoyant force of that object is less than the weight of that object.

5. How do we measure density?  g/cm 3 (grams per cubic centimeter)

6. Describe Archimedes Principle. Give an example of this with the forces involved.  The buoyant force of an object is equal to the weight of the displaced water.  Any examples from class will work.

7. Describe Pascal’s Principle. Give an example of this with the forces involved.  When you apply a force on a fluid, the pressure increases as the force increases.  Any examples from class will work.

8. Describe Bernoulli’s Principle. Give an example of this with the forces involved.  When the speed of a fluid increase, the pressure of the fluid decreases.  Any examples from class will work.

9. What is the purpose of a hydraulic system?  In a hydraulic system, the force is increased to increase the pressure of the fluid to do work.

10. What is used to measure atmospheric pressure?  Barometer

11. What is the density of water?  1 g/cm 3

12. Describe the density of an object that will sink in water.  The density of that object is greater than water’s density.

13. What is the pressure that a 40N object exerts on an area of 8 m 2 ?  Pressure = Force Area  40N 8 m 2 = 5 Pa

14. Compare & contrast pressure and force.  Pressure is a force in a given area.  Force is a push or a pull.

15. How does buoyant force occur?  The pressure exerted by the fluid on the bottom of an object is greater than the pressure exerted on the top.  That means that the upward force on the bottom of the object is greater than the downward force on the top of the object.  There is a net upward on the object.

16. Explain what happens when you try to push an object that floats downward.  The buoyant force pushing up is greater than the force of gravity pushing down  You feel the unbalanced force pushing on your hand.

17. Compare the mass, volume, and density of 10 kg of cotton swabs with 10 kg of steel.  They both have the same mass.  Their volumes would be different.  The kilogram of steel would have a much smaller volume than the kilogram of cotton.  The density of steel would be greater.

18. Describe a hot air balloon in terms of density of hot and cool air.  When the balloon is on the ground and filled with cool air, the weight of the balloon is greater than the surrounding air.  When the air in the balloon is heated, the weight of the balloon is less than the weight of the cool air it displaces, so it floats.