## cassieforlife5 one year ago How to find final momentum of inelastic collision? I'm doing an activity for physics and I have to find the final momentum after two items collide in an inelastic collision. I have the two initial momentums and two final momentums, but the sheet is only looking for one final momentum. Do I add the two final momentums to get the final momentum?

1. IrishBoy123

yes just remember momentum is a vector so it has direction

2. IrishBoy123

and it should equal the total initial momentum (or your experiment has discovered a new law)!!!

3. Michele_Laino

I think that you have to make the vector sum of the two final momentums. Please also check that vector sum has to be equal to the vector sum of the two initial momentums

4. asib1214

@Michele_Laino

5. asib1214

how do i find the amplitde

6. ybarrap

Convert this to a sine wave with Amplitude on y-axis, time on x-axis: |dw:1435610998159:dw| $$A$$ is amplitude (in cm) $$T$$ is period (in seconds) or number of seconds per cycle Frequency is $$\frac{1}{T}$$ Hz or number of cycles per second Peak-to-Peak is 18 cm so amplitude is half of this It takes 3 seconds to move the block 3 cycles so, $$3T=6~\text{seconds}$$ Solve for T In one cycle, the block has moved 18 cm In 3 cycles it has moved three times that distance Does this make sense?

7. anonymous

@asib1214 The amplitude in your problem is the distance the weight has moved from rest to the furthest stretched out point of the spring. This is also the same distance from the block's resting point to the point where the spring is fully compressed. In your picture the distance between the points where the spring is fully compressed and fully stretched is 18cm. ybarrap gave an excellent picture to help explain this idea mathematically. Halfway between where the spring is fully compressed and fully stretched is the natural "resting point" of the mass and thats why you need to divide 18 by 2 for your answer.

8. IrishBoy123

hang on a minute!!! one thread has simply appeared inside another magic? or maybe a bit rude?

9. asib1214

it's aight i've created my own equation to find the amplitude....A= total distance X N (number of cycles)/total time....so it'll be 18 cm X 3 cycles/ 6 seconds = 9 cm