Question

1. which type of friction is described as occurring when an object rolls across a surface?

• a. static friction
• b. sliding friction
• c. rolling friction
• d. fluid resistance

1. why do wheels still need static friction to work properly?

• a. to increase overall resistance
• b. to prevent the wheels from slipping
• c. to generate more heat
• d. to increase rolling friction

1. what is a fluid in the context of friction?

• a. only water
• b. only air
• c. a substance that can flow and take the shape of its container
• d. any solid material that creates resistance

1. air resistance is an example of:

• a. static friction
• b. sliding friction
• c. rolling friction
• d. fluid friction

Explanation:

• Question 5:
• Static friction is when there is no relative motion between surfaces.
• Sliding friction occurs when surfaces slide over each other.
• Rolling friction is for objects rolling (like wheels on a road).
• Fluid resistance is from fluids (not relevant here).
• Question 6:
• Static friction prevents wheels from slipping (like when a car starts, wheels don't spin in place).
• Increasing resistance (a) is not the purpose.
• Generating heat (c) is a side - effect, not the reason.
• Rolling friction (d) is different from static friction.
• Question 7:
• A fluid is a substance that can flow and take the shape of its container (c).
• It's not just water (a) or air (b).
• Solids (d) are not fluids.
• Question 8:
• Air is a fluid.
• Fluid friction acts on objects moving through fluids (like air resistance).
• Static, sliding, and rolling frictions are between solid surfaces.

Answer:

• 5. c. Rolling friction
• 6. b. To prevent the wheels from slipping
• 7. c. A substance that can flow and take the shape of its container
• 8. d. Fluid friction