Momentum Analysis

Question 1

Newton’s First Law:

Answer 1

“A body at rest tends to remain at rest, while a body in motion tends to remain in motion in a straight line, unless acted on by an unbalanced external force.”

Question 2

Mass

Answer 2

is the measure of the amount of material an object contains that causes it to have weight in a gravitational field.

Question 3

Weight

Answer 3

the force exerted on a body by gravity.

Question 4

Acceleration

Answer 4

is the rate change of velocity with respect to time.

Question 5

Newton’s Second Law:

Answer 5

“The acceleration of a body is directly proportional to the force acting on that body, while it is inversely proportional to the mass of the body.”

Question 6

Momentum

Answer 6

is the product of mass and velocity

Question 7

Velocity and Speed:

Answer 7

Speed is a scalar quantity and velocity is a vector quantity

Question 8

Velocity formulas require the units

Answer 8

to be in feet per second and are commonly used

in time and distance applications,

Question 9

Static Friction:

Answer 9

The weight of a non-moving object, pressing down on a surface due to gravity, creates

Question 10

Dynamic Friction

Answer 10

This is what we measure with a drag sled or a test skid.

Question 11

Newton’s Third Law:

Answer 11

for every action there is an equal and opposite reaction

Question 12

To perform a proper collision analysis the following should be conducted

Answer 12

1. measure damage. 2. Photographs. 3. Reports by other investigators 4. The dimensions of the crash vehicles, 5. identify contact damage areas.

Question 13

First Contact:

Answer 13

It is that instant where the objects first touch and force begins to develop between them.

Question 14

Maximum Engagement:

Answer 14

It is at that instant, the vehicle and object have achieved a common velocity or are at the same speed, zero.

Question 15

Last Contact:

Answer 15

Separation occurs when force between the colliding objects ceases, and the objects are no longer in contact or acting on one another.

Question 16

Full Impact:

Answer 16

This occurs when some part of the colliding surfaces attains the same speed during impact.

Question 17

Partial Impact:

Answer 17

Is when no substantial parts of the colliding surfaces attain the same speed during the collision.

Question 18

Velocity Change:

Answer 18

The thrust or force between a vehicle and some other

object results in a collapse of parts of the vehicle.

Question 19

This rotation is dependent on three things.

Answer 19

The strength and direction of the thrust

The point of application

Question 20

Direction Change:

Answer 20

When the force is slightly eccentric and there is a full impact, the vehicle can’t continue in the same direction. When

Question 21

Eccentric forces result in rotation.

Answer 21

the force is not directed towards the center of mass.

Question 22

Collision between Vehicles in Motion:

Answer 22

A number of conclusions can also be made when two moving vehicles collide.

Question 23

Damage and Movement:

Answer 23

Damage is a result of the forces of impact, which

deform the materials of the vehicles.

Question 24

Damage and Speed:

Answer 24

In a two vehicle collision, the stronger vehicle

structurally will suffer the least amount of damage.

Question 25

Damage and Thrust:

Answer 25

When vehicles make initial contact, the force of one

vehicle against another vehicle or other object, begins to crush parts of the vehicle in the direction of the thrust.

Question 26

Contact Damage:

Answer 26

A thorough examination of contact damage areas can

reveal how the vehicles behaved during the collision.

Question 27

There are two rules which govern this:

Answer 27

The greatest collapse in the contact damage area of each vehicle must be against the greatest collapse in the contact damage area of the other.

Question 28

There are two rules which govern this:

Answer 28

Thrust directions must be in line, that is, the thrust of one must be directly opposite to the thrust of the other.

Question 29

Principal Direction of Force (PDOF)

Answer 29

the summation of all collision forces required to deform the vehicle.