Impulse and Automobile Design

Flashcards based on the lecture notes 'Impulse and Automobile Design' covering momentum, the impulse principle, and safety engineering.

What is the definition of momentum?

Momentum ($p$) is the mathematical product of mass and velocity.

Is momentum a scalar or a vector quantity?

Momentum is a vector.

What does the Law of Conservation of Momentum state?

It states that in the absence of external forces, $P_{initial} = P_{final}$.

The Law of Conservation of Momentum is another way of stating which of Newton’s Laws?

Newton’s Third Law.

What is the formal statement of Newton’s Third Law?

“To every action there is an equal and opposite reaction”

On what principle do rockets, propellers, and jet engines operate?

The principle of pushing something in one direction which creates a reaction force pushing in the opposite direction.

In the conservation equation $mu = mv$, what do the variables $u$ and $v$ represent?

$u$ is the initial velocity and $v$ is the final velocity.

What is meant by an "elastic" collision?

An elastic collision is one where no energy is lost.

What main factors determine the outcomes of a 2-particle elastic collision?

Relative mass and velocity.

In Road Traffic Collisions involving pedestrians, how is momentum usually transferred to the pedestrian?

In the form of extra velocity rather than extra mass.

What is the physical product $F \cdot \Delta t$ called?

The IMPULSE of a force.

In the driver deceleration example ($20\,ms^{-1}$ to $0\,ms^{-1}$), which side of the Impulse Equation is considered fixed?

The right side ($m \cdot (v_2 - v_1)$) because mass and the change in velocity cannot change during the interaction.

According to the Impulse Principle, how can you reduce the size of the impact force?

By increasing the interaction time ($\Delta t$).

What is the relationship between interaction time and subsequent injuries in a collision?

Increasing the interaction time reduces the extent of subsequent injuries.

How is the Impulse Principle applied in automobile safety design?

Impact force is reduced by increasing interaction time ($\Delta t$).

What is the purpose of a Collapsible Steering Column?

To absorb impact energy by collapsing, thereby increasing interaction time ($\Delta t$) and reducing impact force.

What specific chest injury can be caused by impact with a rigid steering column?

Flail Chest.

How do collapsible steering columns achieve energy absorption?

They Have deliberately engineered weak spots designed to collapse.

What is the function of padded interiors in an automobile?

To reduce impact force by increasing the impact interaction time ($\Delta t$).

What common sporting equipment is compared to padded car interiors?

Boxing gloves.

What are Crumple Zones?

Deliberately engineered weak spots in the automobile frame (chassis) that deform on impact.

What is the primary function of crumple zones during a collision?

To absorb the force of collision by increasing the interaction time ($\Delta t$).

What does the acronym SIPS stand for?

Side-Impact Protection Systems.

Why is the brain particularly sensitive in the context of side-impact protection?

The brain is more sensitive to impacts from the side than from the front or back.

What two hazards did occupants face in the Model T Ford during an RTC?

A rigid steel steering column and a plate-glass windscreen.

When and where were the benefits of seatbelts and safety harnesses first widely appreciated?

During WWII, specifically in relation to aircraft carrier landings.

When were two-point “lap-sash” seatbelts first introduced?

In the 1950s.

What were the drawbacks of early two-point “lap-sash” seatbelts?

Facial and internal injuries were common, and "submarining" was an issue.

Define "submarining" in the context of seatbelt safety.

Sliding under the lap-belt during a Road Traffic Collision.

Who introduced the three-point (static lap-shoulder) seatbelt and in what year?

Volvo in 1953.

What was Volvo’s stance on the patent for the three-point seatbelt design?

Volvo insisted that the design should not be patented nor protected.

In what year were Inertia-Reel seatbelts introduced?

1963.

What does a belt-actuated inertia reel rely on to operate?

An initial rapid unspooling of the belt.

What mechanism stops the belt in a belt-actuated inertia reel?

A centrifugally-operated mechanism linked to a pawl that engages a toothed wheel.

What triggers a retardation-operated inertia reel?

The actual vehicle's retardation (slowing down).

How does the mechanism in a retardation-operated reel function?

A ball rolls forward or a pendulum weight swings forward to operate a pawl on the belt reel.

What is a practical advantage for the user of a retardation-operated inertia reel?

It allows belted-in occupants a greater general freedom of movement.

What did the EU legislation introduced in 2006 require?

It requires all occupants of automobiles to wear seatbelts.