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Flashcards in TAR I Chapter Quizes Deck (61)
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1

What is acceleration?

The rate of change in velocity with respect to time.

2

What is the acceleration equation?

Acceleration = change in velocity / change in time or delta v / delta t

3

What is constant acceleration?

A type of motion in which the velocity of an object changes an equal amount in equal time periods

4

How many basic values are considered in the kinematic equation?

Five:
Velocity - initial
Velocity - final
Acceleration
Distance
Time

5

The kinematic equations are equations for motion with __________ ____________

Constant Acceleration

6

What will cause a change in acceleration while a vehicle is in full braking?

A change in the surface

7

Do kinematic equations apply to a moving vehicle that is not braking or accelerating?

No, kinematic equations are only used when there is constant acceleration (either positive or negative).

8

If a vehicle passes over multiple surfaces, the initial velocity calculated over the last surface is the _______ _______ used to calculate the initial velocity at the prior surface.

Final Velocity

9

True or False: When a vehicle impacts an object and comes to rest, the change in velocity from the impact can be used as the final velocity in calculating velocity over distances prior to the impact

True

10

What are the three circumstances that will cause a Tire Friction Mark (TFM)?

- Extreme Acceleration
- Extreme Deceleration
- Extreme Changes of Direction

11

Describe a tire abrasion with smear

- A smear of tar/asphalt along with abrasions of tire material. They're long lived and most common on asphalt-concrete surfaces.

12

What is the primary marking mechanism on a Portland Concrete Cement (PCC) surface?

Tire abrasion

13

TRUE or FALSE: Erasing caused by a locked wheel tire is long lived/long lasting.

False

14

Name the four types of tire friction marks?

S.L.I.P.
Side Skid
Lock Wheel
Impending
Critical Speed Scuff Mark (Yaw Mark)

15

Define a side skid TFM

A mark left by a rotating or non-rotating tire that is sliding or slipping sideways to its direction of travel

16

Define a locked wheel skid TFM

A mark left by a non-rotating tire that is sliding along its direction of travel

17

Define an Impending skid TFM

A mark left by a tire that is rotating slower than the forward velocity of the vehicle

18

Define a Critical Speed Scuff Mark (Yaw Mark)

A mark left by a rotating tire that is slipping sideways and diagonally to its direction of travel

19

What are characteristics of a CSS mark

- Starting thin and widening
- Arced
Striations in a direction at an angle to the direction the vehicle is traveling

20

When does a CSS mark transition into a side skid?

- When the heading direction of the vehicle exceeds 20 degrees from center mass path of travel of the vehicle (or 1/3 the wheelbase).

21

The best method for measuring the distance of a straight lined locked wheel tire friction mark used for calculating velocity is:

A: Averaging the TFM
B: Using the longest skid mark

B: The longest skid mark

22

True or False: When a vehicle is rotating during deceleration, the best method for determining the distance the vehicle traveled is the COM movement of the vehicle.

TRUE

23

When might a vehicle be braking and the tire doesn't leave a TFM?

- All wheels are braking but not enough to lock the wheels

- Some wheels were not braking at all (i.e. 1 brake is disabled or not functioning)

24

Describe a gouge

- Occurs when strong metal components dig into the road surface.

25

Describe a chop

Deep gouges where chunks of the road surface have been dug out. A good indicator of maximum engagement

26

What are the three types of friction?

- Static
- Dynamic
- Rolling

27

Describe Static Friction

The friction force when an object is just beginning to slide (i.e. trying to push a fridge)

28

Describe Dynamic Friction

Once the object is sliding, the force required for the object to continue sliding is less

29

Describe Rolling Friction

The resisting forces when a tire is rolling with no brakind

30

True or False: Coefficient of Friction / Drag Factor is "unit-less"

TRUE