Real world problem, with KE problem

[WhiteHawk]

What forum should I post this in, my friend died in a horrible car accident, some of us just want more answers I guess...

Object A is in straight line motion
Object B is static

Object A impacts Object B

Object A moves straight forward 60 m and rests
Object B moves straight forward 76 m and rests

Object A has a mass of 1,500 kg
Object B has a mass of 1,500 kg

What was the velocity of Object A when it impacted Object B?

To account for some rolling resistances, Object A was a car that rolled and tore up large patches of sod, Object B was a rectangular boulder that rolled ~20 times. I guesstimated 124 mph (see below), but I can't believe it (I feel like I missed a bunch of things or didn't draw the problem right).

 

[jedishrfu]

Are you sure the boulder is the same weight as the car. from your description it seems it is lighter.

On a pool table, when the cue ball strikes a stationary ball, the cue ball stops and the stationary ball continues with the same velocity unless the cue ball has some additional spin. In your case, after the collision both objects are moving forward.

I think you can solve it via conservation of momentum.

 

[WhiteHawk]

Are you sure the boulder is the same weight as the car. from your description it seems it is lighter.

On a pool table, when the cue ball strikes a stationary ball, the cue ball stops and the stationary ball continues with the same velocity unless the cue ball has some additional spin. In your case, after the collision both objects are moving forward.

The boulder is about the volume of a fluffy lazy boy chair (minus the back). My landscape friend estimated that weighed 1.5-2 tons. Imagine literally, a car running directly into this boulder, transferring enough energy to launch the rock 62 meters (I just measured my stride, 737 mm x 84 strides), and keep enough energy to move / drag / roll the car 45 meters. I don't even know why I am doing this, I guess this is what a nerd does when his friend dies.

 

[jedishrfu]

The boulder is about the volume of a fluffy lazy boy chair (minus the back). My landscape friend estimated that weighed 1.5-2 tons. Imagine literally, a car running directly into this boulder, transferring enough energy to launch the rock 62 meters (I just measured my stride, 737 mm x 84 strides), and keep enough energy to move / drag / roll the car 45 meters. I don't even know why I am doing this, I guess this is what a nerd does when his friend dies.

What answer do you hope to get from this? I'm thinking that any calculation will be far off from reality. Are you trying to determine speed? is there some negligence involved?

 

[pmacias]

First of all, I am sorry for your loss. It is understandable that you and your friends are seeking more answers about the car accident.

I would recommend posting this question in a forum or group that specializes in physics or engineering. This problem involves the concept of kinetic energy (KE) and the calculation of velocity, which are topics that are often discussed in these forums. You may also consider reaching out to a physics or engineering professor at a university for their expertise and guidance.

Now, to address the problem itself, we can calculate the velocity of Object A using the equation KE = 1/2 * m * v^2, where KE is the kinetic energy, m is the mass, and v is the velocity. We know the mass of Object A is 1,500 kg and we need to solve for v.

To account for the rolling resistances, we need to consider the frictional forces acting on both Object A and Object B. These forces would decrease the velocity of Object A upon impact. We would also need to know the coefficient of rolling resistance for both objects to accurately calculate the final velocity.

Without this information, it is difficult to determine the exact velocity of Object A upon impact. However, based on your estimation of 124 mph, it is possible that you did not account for the rolling resistances and/or underestimated the impact of friction on the objects. It is important to consider all factors and assumptions when solving a problem like this.

In conclusion, I would recommend seeking the help of experts in physics or engineering to accurately calculate the velocity of Object A upon impact. They can also provide valuable insights and explanations about the dynamics of the collision.