Why I changed my order to a 07 Camry

A ping pong ball hitting a stationary paddle will deform absorbing kinetic energy... and then bonce in the opposite direction at appoximately the same speed as it impacted the paddle. If the paddle was moving toward the ball on impact... then the ping pong ball would bouce off of the paddle at a higher speed (absorbing more energy)... This is exactly as you are describing. The problem is that it is not representative of the problem here.

If two ping pong balls were travelling in the opposite direction... and collided... then they would each absorb the equivalent of their kinetic energy... then reverse direction, and travel in the opposite direction at the same speed as if they each had hit a stationary paddle.

Finally.... I am 100% sure of this... and I suggest that you examine why you are improperly thinking about the problem. To put things into perspective... I recently lost my son when he was killed by striking a truely immovable object. I know what I am talking about all too dearly... and trust me that my analysis is not wrong.

/Jim

 

stand a ping pong paddle up against a wall and throw a ping pong at it. that is a car hitting a immovable object. we all all seen the swinging steel ball experiment right?? when you swing one ball toward the rack, one ball on the end bounces out. if you swing 2 balls toward the rack, 2 balls bounce out, etc. that works because all the balls are the same. a ping pong flies off a paddle because the paddle is moving, not stationary, and weighs a lot more than the ping pong ball so it imparts much more energy to the ball. a baseball flies farther when thrown harder because of the equal and opposite rule. it flies in at 100 mph, it hits something, it will be bounced back at the same speed minus compression losses right?

to say a car hitting a wall at 25 mph is the same as 2 cars hitting each other at 25 mph is not quite right either. sure you have double the crumple zone but also double the energy.

and in the crash tests, yes the heavier vehicle is unfairly penalized because there is more energy involved when an immovable object is involved. likewise, a heavier car will fair better in a crash with all other things being equal with a lighter vehicle. but the difference in weight between the Prius and the Camry are not enough to make a difference imm especially when so many variables apply in most accident situations.

for the most part, people who make purchase decisions based on weight are wasting their money. i think your decision to buy a Camry is fine and there are many reasons to purchase one as you have pointed out.

 

How does that Newts Law go: For every action there is an equal and opposite reaction. The real issue is the Kinetic energy (energy of motion) being dissipated completely during a collision. To summarize the examples used:

Viz
1) One Prius at 25 mph colliding with a immovable wall: KE = X (remember algebra?)

2) Two Prius at 25 mph colliding head-on: KE = 2X

3) One Prius at 50 mph colliding with a immovable wall: KE = 4X

Prius at 3200 lbs = 100 slugs = 3200 lbf-sec^2/ft
For 25mph, which is about 37 ft/sec; V^2 = 1370 ft^2/sec^2
For 50 mph, or 74 ft/sec; V^2 = 5480 ft^2/sec^2 {4 times greater}

KE @ 25 mph = X = (1/2)*m*V^2 = (1/2)*3200*1370 lbf-ft = 2,192,000 lbf-ft.

KE @ 50 mph = 4X = 8,768,000 lbf-ft.

 

Denny,

I believe that you would agree that since #1 above has one vehicle absorbing the energy of the collision... and that #2 above has two vehicles absorbing the energy of the collision.... assuming that the mass, and design of the two cars were equal... then in fact... the damage to a car in either situation would be the same. Which is of course what I have been arguing all along.

/Jim

 

If a car hits a wall energy is transferred into the wall and the car in equal amounts.. can we agree on that?

If so, when you add another car that has real kinetic energy in the equation traveling the opposite direction... that energy is going to go some where too correct?..

1/2 of its energy will go into itself and 1/2 into the other car "instead of the wall".. remember the wall has been removed and replaced by the opposing car.

So now both cars are getting half of thier energy and half of the energy from the other car.... so twice the energy "at least" is being transferred into each car.

The "extra" energy that came from the other car had the exact amount of energy to offer to the equation as the one car did by itself?

All of that extra energy from the 2nd car did not go into the 2nd car.. 1/2 when into the 1st car and by the same token the 1/2 of the 1st cars energy went into the 2nd car... remember the wall is gone so the opposing car takes that energy instead....

Now I'm talking in circles?

If you can't see the other car "on both cases" takes the energy that the wall would have taken and so each unsued more damage, then I can't help you any more.

 

When Jim and I were referring to a fixed barrier, we meant a barrier that absorbs a negligible amount of energy compared to the car. The car would absorb (practically) all of the energy. I think this is the source of miscommunication, so I hope we all agree now.

I bet the Camry Hybrid will be more expensive than the V6 version. Though if they did price it lower than the V6, it would sell like hotcakes, bringing down the cost of the hybrid components due to sales volume. Not sure about including the rear camera though... it seems that Prius buyers tend to be more excited about tech than Camry buyers. Most cars in the Camry's market segment do not include a rear view camera. I think they're mainly limited to hulking SUVs where rear visibility is a real problem. This is all speculation.

 

My Observations:
*To me the Camry looks like a bigger car on the outside compared to how it feels on the inside.
*The prius looks like a smaller car on the outside than what it feels on the inside.
*The Camry has a bit more get up and go but worse MPG.
*Both cars could be impressive to carry clients around.
*Both cars have luxury and elegance worthy of being proud.
*The prius is more versatile and has a tax credit.

 

The split window I don't see as a problem. The split affords a window which allows much lower visibility than other cars have. I would be hard to back over a bicycle because of the improved lower view.
While driving the lower window is not used and even if you tried, all you would see is pavement.

I think most of the hype about the split is psychological. I don't even notice it and its nice to have the lower window while backing. The camera is just a luxury item... not really necessary and I wouldn't back up using it.. I would still back up and only use the camera as a secondary tool.

 

WRONG. I'm appalled at how ignorant people are of basic physics. When a baseball player swings a bat at a ball coming towards him, the ball flies very far. When he bunts the ball, holding the bat perfectly still, the bar travels a very short distance. I can't believe you people are so ignorant! When you swing a ping-pong paddle at a ball, your paddle is moving FORWARD! Why? Because it makes the ball bounce farther!

And so-called "immovable" objects are NOT immune to the laws of physics. Nothing is immune to the laws of physics, despite what you may believe. Christ.

 

Sadly, no, they can't agree on that. You are correct, of course, but that is the basic law of physics that absolutely no one else here understands. They think walls are immune to the laws of physics and they don't absorb energy.

There is a saying "everything's relative", coined by someone called Einstein. This "Einstein", a physicist of some reknown, was referring to a principle that describes why an object moving towards another at 50 mph is the same as two objects moving towards each other each at 25 mph; the relative difference is 50 mph in either case so the result is the same.

OK, sorry, just had to get that off my chest. Back to Camry Hybrid discussion:
Toyota stated it will be cheaper than a loaded V-6 XLE, which unfortunately means the base hybrid will probably be around $28k, possibly $27k. With navigation it can be expected to be close to the HAH price.

 

One of the things I like most about this website is that people are usually very friendly with each other, even when they don't agree. Please try not to spoil that.

As far as I can tell, what you say about bunting baseballs is correct. What Jim said about the two ping pong balls is also correct assuming a perfectly elastic collision. Just write out the equations for conservation of momentum and energy, and you only get one solution: that the balls bounce off of each other and reverse direction exactly.

I'll restate that I believe there is only a miscommunication going on here because Jim and I are purists and like to assume things like perfect elasticity and perfectly rigid non-energy-absorbing objects. These theoretical objects DO NOT exist in the real world, but they do allow scientists to simplify modeling of the real world. I'm surprised so many people have a beef with them because they were used heavily in my high school physics homework (and I assume other people's homework).

If all you want to hear is that you're right, then fine: You're right. Perfectly elastic collisions don't exist. Perfectly fixed barriers that do not absorb energy do not exist. You can criticize the use of these constructs all you want, but in reality they're used every day by scientists and are extremely useful.

 

I posted the erroneous statement originally and still thought I was right but the 'guidance' here prompted me to do some research on the 'net and found several sources on google using ' physics of car crashes' that proved my statement wrong.

Newtons Laws state that momentum is conserved in a crash of two vehicles. Some of it is absorbed by the vehicles themselves or transferred into energy in the form of heat and noise. In the crash of two vehicles of the same mass and velocity there is twice the amount of momentum there is in the crash of one vehicle into a tree or wall for example.

A more complicated but personal consideration is what is the effect on the occupant(s) in a crash.
One vehicle crash into an immovable tree ( the occupant(s) absorb nearly all the energy );
Two vehicles of the same 'momentum' crash ( the occupant(s) of both vehicles share the energy equally );
Two vehicles of different 'momentums' crash ( the occupants(s) of the lower momentum vehicle absorb a relatively larger share of the energy of the crash )

Before running out to buy Escalades enmasse. Momentum is variable by mass and velocity. Therefore:

If a Prius moving at 60 mph hits head on with another Prius of similar mass which is moving slowly. The occupant(s) in the 2nd Prius will absorb more of the energy of the crash than their momentum dictates and the occupants of the moving Prius will absorb somewhat less energy.

Similarly a Prius going 60 mph smashing head on into a slowly moving Escalade may transfer some crash energy to the Escalade occupant(s) just as in the Prius/Prius crash. It depends however on the mass and velocity of each vehicle;
say an Escalade is twice the mass of a Prius then if the Prius was going 60 and the Escalade was going 30 the effect on the occupants is equal since the momentums are equal.

Dissapating this crash energy is the key to keeping the occupants inside safe. This is the purpose of auto safety design.

Doing the research - and I believe I expressed it correctly above - showed me that there was only a certain amount of momentum in each type of crash. It depends on the amount of mass ( number of vehicles ) and velocity ( of each ).

I guess then I can postulate some rules for myself in the event of a crash.

1) Don't.
if 1) is not possible;

1a) Reduce speed thereby reducing momentum!!!
2) Try to find a medium to absorb some of the crash energy like a deformable barrier, water or soft earth.
3) Don't hit anything moving faster than I am;
4) Don't hit anything that won'd deform or move with me; see 2) above.

I'm open to corrections since this is from reading over the weekend and I dont have a textbook in front of me.

 

Well, as a friend of mine once said:

If you are about to crash head on with another car, and can't avoid the accident but want to live - FLOOR IT!!!

i.e. in the Prius' case: Full power both engines

 

This is extremely bad advice. Speeding up will only increase the amount of kinetic energy the crash will have to dissapate. It does not decrease the fraction of kinetic energy that your vehicle will have to absorb. Please, please just hit the brakes as hard as possible!

The fraction of kinetic energy the structure of your car has to absorb depends only on the structures of the cars involved, not the speed of your car versus the speed of the other car. A simple example: Car A crashing into a stationary Car B will cause damage in exactly the same way as Car B crashing (at the same speed) into a stationary Car A. A simple way of visualizing this is just changing your frame of reference from Car A's point of view to Car B's point of view.

Before people jump on me, let me state my simplifying assumptions: accidents occur in a vacuum on a frictionless surface. Also, the cars deform in a uniform fasion, so no front ends made of lead covered in a layer of silly putty.

Another good example is imagine a baseball made of clay hitting a stationary baseball made of lead. The clay baseball will deform to absorb the energy of the collision. If it were the lead baseball hitting a stationary clay baseball, the clay baseball would again deform. So it's the structure and material of the objects that dictates what proportion of energy is absorbed by whom.

 

The effect of equal momentum will bring both cars to a stop. However the Prius went from 60 to 0 and the Escalade went from 30 to 0.

So it would be like the Prius hitting a brick wall at 60 mph and the Escalade hitting a brick wall at 30mph.

It would also be like a Prius hitting a parked Escalade at 90mph. Or like an Escalade hitting a parked Prius at 90mph.

And if either car increases speed as habel's friend suggests, that will only make it like hitting the other car at a speed faster than 90 mph.