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Need help with physics problem

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  • Cars
Last response: in Cars
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October 8, 2009 2:03:14 AM

Object one and object two are moving towards each other, object one has a mass of 10kg and an intial velocity of 10m/s and object two has a mass of 20kg and an initial velocity of -5m/s........what will be the final velocity of object one and object two????

More about : physics problem

October 8, 2009 2:32:22 AM

ZERO velocity
Final answer
October 9, 2009 7:50:50 PM

Depending on the impact location / face, it should be zero, if they hit dead on. (say 2 spheres or cubes).
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October 9, 2009 8:53:05 PM

Are we sure - as the calculation for kinetic energy is (mass x velocity)/2 - the faster but lighter body has a higher stored kinetic energy... Should this not keep the faster object moving?

It's the bullet scenario, fire a bullet into an object that is 1000 x the mass of the bullet, and that object will move reactionary as a faster rate than 1/1000th of the pace of the original bullet....
October 29, 2009 8:10:01 AM

jamesgoddard said:
Are we sure - as the calculation for kinetic energy is (mass x velocity)/2 - the faster but lighter body has a higher stored kinetic energy... Should this not keep the faster object moving?


(mass x velocity)/2 = (20 x 5)/2 = 50
(mass x velocity)/2 = (10 x 10)/2 = 50

Yes, we're sure. Now, in reality, the two objects will almost certainly not hit head-on, so they will both continue moving, but in different directions. However, in this physics problem, they will both cease to move after impact.
October 29, 2009 9:20:48 AM

No your formula is wrong, you forgat that velosity is squared

final answer is +7.07m/s for object one.
(+ = moving in the same direction as it was)
Anonymous
October 29, 2009 1:18:46 PM

impulse, ft=mv-mu

Or putting it another way, if they stick together

Mass(total) x Velocity(final) = mass(object1) x velocity(object1) + mass(object2) x velocity(object2)
Anonymous
October 29, 2009 1:31:21 PM

Oops I forgot

Is the collision inelastic or elastic?

If it is totally inelastic, then the final velocity is zero. as total momentum is zero

If it is elastic, then use m4.v4 + m3.v3 = m2.v2 + m1.v1
momentum is conserved,

Cannot remeber exact solution, google it!
December 22, 2009 5:55:02 AM

Hey guys/gals, who said they are moving on a linear plane towards each other, impact may not be even probable.

How much are we allowed to assume?
December 22, 2009 5:38:38 PM

momentum is conserved whether the collision is elastic or inelastic

if it is elastic, then kinetic energy is also conserved

if it is inelastic, the problem is not solveable as stated, because you don't know how much is lost as heat or otherwise

if the collision is elastic, then you have to set up two equations where initial and final momentum AND kinetic energy are equal (mv and .5mv^2) in this case you have two variables and two equations and you solve the system and have your two final velocities
January 20, 2010 6:10:24 PM

why is this in the car section?
February 4, 2010 11:37:24 AM

This thread is outside the scope of this forum section, please post in different section.

[thread locked]
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