Momentum problem!!!!!?

Question

It used to be common wisdom to build cars to be as rigid as possible to withstand collisions. Today, though, cars are designed to have “crumple zones” that collapse upon impact. What advantage does this have?

Answer 1

from the equation of impulse force, F= (change of momentum) / (time).
we can see clearly from the equation of impulse force above, if we increase the time, the impulse force will decrease if the change of momentum is unchanged.

for the car collision case; if we can increase the time of collision, that will means we decrease the impact or impulse force. how we increased the time of collision???
we can increase it by designing a part of car that break easily. it like when we falls to a sponge or cement. which one will hurt more?


the main objective to design the "crumple zone" is to increase the time of collision between two masses. as the time of collision increased, the impact force will go decreased.







p/s: physic problem is solve using equations. first we described one phenomenon in an equation, then we explain to others using that equation.

Answer 2

When you are in a car and you and the car are both traveling at 60 miles per hour and the car suddenly stops (because it ran into something) you continue to travel at 60 MPH until something stops you as well. That's momentum (AKA inertia). It's equivalent to being shot out of a cannon at 60 MPH into the dash/steering wheel/windshield of your car.

The engineering approach of a rigid car is OK if the goal is to minimize damage to the car. Jay Leno told a joke once about how his dad owned a Buick and it was a "real car". The punchline was if you had an accident in that car they just hosed you off the dashboard and sold the car to somebody else. Now the thinking is that a better goal would be minimizing damage to the occupants of teh car (duh!). So now cars are (to various extents) design to crumple (compress similar to an accordion) so that the car absorbs more of the energy of the collision and decelerates less quickly.

The cabin is still designed to be rigid to provide a protective box around the occupants.

Along the same lines some engines are designed to drop down during a collision so they don't get shoved back into the passenger compartment during a collision.

Answer 3

probably to absorb the impact from the crash. It's probably a lot harder on the driver's head to hit a car and have the car bounce off because of the rigid design. If the car crumples, some of the energy is absorbed and therefore doesn't affect the driver or passengers as much.

Answer 4

If your car is too rigid, the car's impact will be greater. What's worst is that your body move with the car, so when the car suddenly stop, your body still move forward. those "crumple zones" are design to slow the car down, thus slowing you down, and cause less impact.

Answer 5

Consumers who run out to buy their shiny new 2007 model never have to worry about being able to trade it in for the new 2009 model

Answer 6

its strickly a safety feature......to reduce the momentuim of the passenger,s.......therefore reduceing the potencial of whiplash!or other potencial injury,s.

Answer 7

Easy ... don't you get it. It softens the impact. Duh ?

Yours;
Jonnie