Interactive Graded Test on Rolling Friction

This is an interactive test that will automatically check your answers and calculate your grade. This test has 15 questions and is based on material from the Friction section of lessons:

Rolling friction

• Role of Friction in Starting Rolling Motion
• Rolling Friction
• Rolling Friction and Automobile Tires
• Traction Friction of Tires

Fluid friction

• Changing Fluid Friction

It is a good idea to study these lessons before taking this graded test.

(Also see Interactive Graded Test on Sliding Friction.)

QUIZ

Self-check your understanding

1. Why should you accelerate your car slowly when on slippery pavement?

   You don't want the torque to be greater than the low static frictionThat is correct.The law states that you are required to start slowly or you will be ticketedGood try, but not right. Select another answer.The friction is much higher on slippery pavement, making it dangerousSorry, not correct. Try another button.

2. Where is the best place to push on a wheel to get it rolling in that direction?

   Near the topThat is correct.Near the bottomGood try, but not right. Select another answer.You can't make it roll by pushingSorry, not correct. Try another button.

3. Do mud tires work on hard pavement?

   No, they only work in mudGood try, but not right. Select another answer.Yes, because there still is plenty of static friction to help roll the tireThat is correct.No one is really sure, since it never has been triedSorry, not correct. Try another button.

4. Which has greater rolling friction, a steel train wheel or an automobile tire?

   The train wheel, because it is heavierGood try, but not right. Select another answer.The automobile tire, because rubber is sticky and not smoothThat is correct.Neither has rolling frictionSorry, not correct. Try another button.

5. What happens to the rolling friction if you add weight to a car?

   The tire deforms more with the extra weight and has more resistanceThat is correct.The extra weight will allow the car to roll faster down hillGood try, but not right. Select another answer.The tire becomes harder with the extra weight, thus reducing the frictionSorry, not correct. Try another button.

6. What is the coefficient of rolling friction proportional to?

   Proportional to the width of the wheel and inversely proportional to the radiusThat is correct.Proportional to the width and radius of the wheelGood try, but not right. Select another answer.Proportional to the width of the wheel and the kinetic friction of the surfaceSorry, not correct. Try another button.

7. Does the tire's coefficient of rolling friction change with the weight of the car?

   Yes, because weight determines amount of deformationThat is correct.No, because weight is just the normal force and is independent of the coefficent of frictionGood try, but not right. Select another answer.Yes and no, depending on the type of rubber used in the tiresSorry, not correct. Try another button.

8. Why is the temperature of the tire a factor in friction?

   It is an indication whether it will rain, which affects rolling frictionGood try, but not right. Select another answer.Rubber melts when the temperature is too high, thus lowering frictionSorry, not correct. Try another button.Air pressure in the tire increases with temperature, thus changing the deformationThat is correct.

9. Is the rolling friction of a tire the only thing that slows down a car?

   Yes, provided you include the weight of the carGood try, but not right. Select another answer.No, since friction on the axles and air resistance must be includedThat is correct.It depends on how fast the car is going at the timeSorry, not correct. Try another button.

10. What is a major factor in the traction of a tire?

    The size of the tire is important in tractionGood try, but not right. Select another answer.The edges increase the traction in various directionsThat is correct.Spinning your wheels increases the tractionSorry, not correct. Try another button.

11. What is a disadvantage of using snow tires on dry pavement?

    The deep, wide treads result in a noisy ride and increased rolling frictionThat is correct.It is against the law to use such tires when there is no snowGood try, but not right. Select another answer.The snow treads tend to slip on dry pavementSorry, not correct. Try another button.

12. Why are race tires so wide?

    The width prevents the car from tipping overGood try, but not right. Select another answer.The rolling friction is less with greater surface areaSorry, not correct. Try another button.Their traction is proportional to the surface areaThat is correct.

13. Why does heavy, thick oil produce more friction than thin oil?

    Thick oil has higher viscosity and is more difficult to move than thin oilThat is correct.Actually, thin oil produces more frictionGood try, but not right. Select another answer.Thick oil contains mud, which has much frictionSorry, not correct. Try another button.

14. Why are the rivets and screws on an airplane skin flush with the surface?

    To improve the looks and make it easier to paintGood try, but not right. Select another answer.So they won't fall out due to air frictionSorry, not correct. Try another button.To reduce air friction along the surfaceThat is correct.

15. Why are fish shaped the way they are?

    To reduce water resistance when they swimThat is correct.To increase the friction of their mouths and help their ability to eatGood try, but not right. Select another answer.No one knows for sureSorry, not correct. Try another button.

Pick an answer to see instant feedback. Re-read the lesson if you miss one.

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