Need help with a question

[fallfast69 2]

I'm helping my kid with a question on a test and I can't figure this one out. I already have the answer, but can someone explain how to solve it?

A 0.24-kilogram glider moving with a velocity of 0.6 m/s collides with and sticks to a 0.26-kilogram glider moving with a velocity of 0.2 m/s. The final velocity v of the two gliders is

A. 0.392 m/s.
B. 0.184 m/s.
C. 0.092 m/s.
D. -0.092 m/s.

Thanks,

Jon

[JohnMitchell 14]

Is it a head on collision or same direction overtaking?

[fallfast69 2]

I don't know, that's all there is to the question

[d_squared431 0]

Ask grannyinthesky.She lives/loves math stuff...

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[shropshire 0]

(A) - if both going in the same direction

Conservation of momentums says that

MV = m1v1 +m2v2

MV = (.24 *.6 ) + (.26 * .2)

M = .24 + .26 = 0.5Kg

0.5V = 0.196
V = 0.196/0.5 = 0.392

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[ryoder 1,381]

See " Perfectly inelastic collision":

http://en.wikipedia.org/wiki/Inelastic_collision#Perfectly_inelastic_collision

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[JohanW 0]

Quote

I'm helping my kid with a question on a test and I can't figure this one out. I already have the answer, but can someone explain how to solve it?

A 0.24-kilogram glider moving with a velocity of 0.6 m/s collides with and sticks to a 0.26-kilogram glider moving with a velocity of 0.2 m/s. The final velocity v of the two gliders is

A. 0.392 m/s.
B. 0.184 m/s.
C. 0.092 m/s.
D. -0.092 m/s.

Thanks,

Jon

A is the correct answer if the first glider is overtaking the second. B is the correct answer if they are colliding, but the heavier, slower glider's speed should have been given as -0.2m/s.

Conservation of momentum (P (I think) = m × v): end speed is ((0.24×0.6)+(0.26×0.2))/(0.24+0.26).

Johan.
I am. I think.

[JohnMitchell 14]

Let's go with head on. I hope I remember enough physics.

Momentum = mass X velocity , or p=mv

So .24 x .6 = .144
.26 x .2 = .052

.144 - .052 = .092 for your new momentum, Divide by the new weight, .50 kilos, for the new velocity.

.092 / .5 = .184 m/s

Same direction collision gave me .392 m/s

[fallfast69 2]

Thanks everyone...the correct answer is "A". I'm pretty good at figuring shit out, but this one was clearly way above my education level

Jon

[ryoder 1,381]

Quote

Let's go with head on. I hope I remember enough physics.

Momentum = mass X velocity , or p=mv

So .24 x .6 = .144
.26 x .2 = .052

.144 - .052 = .092 for your new momentum, Divide by the new weight, .50 kilos, for the new velocity.

.092 / .5 = .184 m/s

Same direction collision gave me .392 m/s

Shouldn't the ATC guy be more concerned about who put the gliders on a collision course?

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[Belgian_Draft 0]

Gets even better if they collide at some God-awful angle. Gets real ugly if the velocities are not on the same plane.

HAMMER:
Originally employed as a weapon of war, the hammer nowadays is used as a
kind of divining rod to locate the most expensive parts adjacent the
object we are trying to hit.

[JohnMitchell 14]

Quote

Shouldn't the ATC guy be more concerned about who put the gliders on a collision course?

Hey, hope for the best, but plan for the worst.