FM mechanics work & energy | Mathematics | Page 1

lean shale May 3, 2025, 2:47 PM

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twin pumiceBOT May 3, 2025, 2:47 PM

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lean shale

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nimble radish May 3, 2025, 2:48 PM

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lean shale

What have you tried?

lean shale May 3, 2025, 2:48 PM

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nimble radish What have you tried?

a lot

nimble radish May 3, 2025, 2:49 PM

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Can you show it?

lean shale May 3, 2025, 2:50 PM

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nah im on my pc

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ive done part 1

nimble radish May 3, 2025, 2:50 PM

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What did you get?

lean shale May 3, 2025, 2:50 PM

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156.8J

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everything i try doesnt give the answer in the textbook

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for part 2 and 3

nimble radish May 3, 2025, 2:51 PM

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lean shale 156.8J

Yeah, that's correct.

nimble radish May 3, 2025, 2:52 PM

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lean shale for part 2 and 3

What did you get?

lean shale May 3, 2025, 2:52 PM

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nimble radish What did you get?

part 2

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1.96(80 - x)

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but idk how to put that in ts later

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or is thata

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already in that form

nimble radish May 3, 2025, 2:53 PM

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Yeah, that's correct.

lean shale May 3, 2025, 2:53 PM

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idk where they get the 2nd part from

nimble radish May 3, 2025, 2:53 PM

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lean shale idk where they get the 2nd part from

From the equation of motion.

lean shale May 3, 2025, 2:53 PM

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how does -1.96x = 09.6t^2

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like i tried KE gained = GPE lost for part 3

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and subbed iti n

nimble radish May 3, 2025, 2:54 PM

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lean shale how does -1.96x = 09.6t^2

Write the equation of motion for x, considering that the only force acting on the body is the gravitational force.

lean shale May 3, 2025, 2:54 PM

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but i dont get the answer no matter what itry

lean shale May 3, 2025, 2:54 PM

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nimble radish Write the equation of motion for x, considering that the only force acting on th...

s = ut + 1/2at^2

nimble radish May 3, 2025, 2:54 PM

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I suggest ditching the exact value of mass for now. Just denote it by m. Easier to work like that.

lean shale May 3, 2025, 2:55 PM

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80 - x = 1/2gt^2

nimble radish May 3, 2025, 2:55 PM

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lean shale s = ut + 1/2at^2

Well, I mean, the initial velocity is zero, and the acceleration is g (if you point the axis down). So, just x = (1/2)gt^2.

lean shale May 3, 2025, 2:56 PM

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nimble radish Well, I mean, the initial velocity is zero, and the acceleration is g (if you po...

ye

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oh

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its just x

nimble radish May 3, 2025, 2:56 PM

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Well, you could pick another initial point, but since we're already given x, I think this is easier.

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So, since we got U = mg(h - x) already, we can just substitute x = (1/2)gt^2 into it.

lean shale May 3, 2025, 2:58 PM

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ye i just was using the wrong value

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part 3 do i just use v2 = u2 + 2as

nimble radish May 3, 2025, 3:01 PM

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Don't really like using s instead of x, since it can be confused with S. But your idea is right.

lean shale May 3, 2025, 3:01 PM

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so i get v2 = 19.6x

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but now idkk how ur supposed to find the range of values for t

nimble radish May 3, 2025, 3:02 PM

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Well, this equation always works, right?

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At least, until the body touches the ground.

lean shale May 3, 2025, 3:03 PM

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i see

nimble radish May 3, 2025, 3:04 PM

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So, find out the time at which it touches the ground, after which you can answer this question.

lean shale May 3, 2025, 3:04 PM

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0 <= t <= 4.04

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ok

nimble radish May 3, 2025, 3:05 PM

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lean shale 0 <= t <= 4.04

Don't forget units.

lean shale May 3, 2025, 3:05 PM

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ye i didnt

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thanks bro

nimble radish May 3, 2025, 3:06 PM

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Well, the rest should be more straightforward.
You're welcome!

lean shale May 3, 2025, 3:06 PM

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ye it was all the 80-x instead of x

nimble radish May 3, 2025, 3:07 PM

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Ah, I see.

copper zincBOT May 4, 2025, 4:00 PM

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@lean shale

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