1. Homework Statement
The isotope 239Pu has a half-life of 24,100 years. After 10,000 years, a sample of the isotope is reduced 1.6 grams. What was the intial size of the same (in grams)? How large was the sample after the first 1,000 years. Round your answer to four decimal places.
2...
1. Homework Statement
(Between 0-3) ∫x3/√(x2+9)
3. The Attempt at a Solution
I attempted U sub, but that didn't work. Neither did integration by parts; however, I do remember my teacher using a method involving sub'ing an "x" or something.
Anybody?
Will edit in attempts as I search...
Hmm okay, got it.
So let's say U = x2
dU = 2x
dv = xe5x2
V=1/10e5x2
Then, plug into the equation, and you get....
(x2)(1/10e5x2) - ∫(1/10e5x2)2x dx
EDIT: Just got it, thanks a lot for your time :).
1. Homework Statement
∫x3e5x2 dx
2. Homework Equations
uv-∫vdv
3. The Attempt at a Solution
I've tried this one a few times, but keep getting answers that are just out there. Could someone, if possible, work out just the beginning.
1. Homework Statement
Find the indefinite integral:
∫ Cos32x Sin22x dx
2. Homework Equations
None required
3. The Attempt at a Solution
Lost on where to start. If someone could just start me off.
1. Homework Statement
I'd like to mention beforehand this is not my work, i'm simply just trying to understand it.
I believe the answer is incorrect, could someone kindly indicate why?
A spherical navigation buoy is tethered to the sea floor by a vertical cable as
shown in the...
1. Homework Statement
Prove that the product of the kinetic energy and orbital radius of a geosynchronous satellite is constant.
2. Homework Equations
Not sure on the orbital radius part
KE=KE = ½mGM/R
3. The Attempt at a Solution
I'm lost on where to begin. How exactly would I 'prove' it?
Thanks for the response Tiny-Tim :)
Okay, so i follow you somewhat. F = -bv (general formula for resistive force).
According to Newton's second law, F=ma which can be rewritten as F=m(dv/dt).
You then equate those two, and you get m(dv/dt)=-bv.
What happens after this? (dv/v) is the...
1. Homework Statement
2. Homework Equations
The above formulas
3. The Attempt at a Solution
I'm lost on where to start with this. The object has an intial velocity in the X direction and has the resistive force of the plontons acting upon it when it lands. What exactly is...
Re: Tricky problem worth 2 points on my final grade :)
That equation was ugly as hell hahaha.
Okay, the velocity of the smaller block was 1.75 m/s
the larger .8 m/s
Re: Tricky problem worth 2 points on my final grade :)
Hmm I could give it a try. In regards to KE,
1/2Mv2= 1/2mv2+1/2Mv2
Not sure how to signify a collision above. Sorry for giving you a hard time. My physics professor isn't much a professor.
Re: Tricky problem worth 2 points on my final grade :)
Okay, well rearranging that equation, you get 2mghv2/m.
O.... Then the masses cancel out and you're left with 2gh=v2.
Sqr[(2)(9.8)(.3)] = 2.619
So M hits m with a velocity of 2.619 m/s.
_______________________________________...
Tricky problem worth 2 points on my final grade :)
1. Homework Statement
2. Homework Equations
I honestly don't know how to tackle this.
I think it's going to contain ƩF=mg, and some basic kinematic equations.
3. The Attempt at a Solution
Where do is start?
1. Homework Statement
I notice that when solving for k, the book often uses a positive version of the formula.
How do you know which to use?
2. Homework Equations
F=kx
F=-kx
3. The Attempt at a Solution
1. Homework Statement
http://www.youtube.com/watch?v=cM3t6Td_rYs&feature=plcp
2. Homework Equations
W=FΔrCosθ
3. The Attempt at a Solution
My questions: 1) At around 2:30, when he draws out the free body diagram, I don't understand how he comes up with these Equations. For example...
Re: A raindrop of mass 3.35x10-5 falls vertically at constant speed under
Force of gravity = 9.8
Displacement = 100
Cos (90) = 1
But if the net force is zero, what do we plug into F for the equation?
1. Homework Statement
A raindrop of mass 3.35x10-5 falls vertically at constant speed under the influence of gravity and air resistance. Model the drop as a particle. As it falls 100m, what is the work done on the raindrop. (a) by the gravitational force and (b) the air resistance.
2...
Understood, so quick question, is the blue line the force? Then the other lines simply components of the force?
Still a little lost. We want to calculate the work required to mvoe the object to the right first. Force is constant right? So would you use fΔrCosθ?
1. Homework Statement
2. Homework Equations
W=∫ Fx dx
3. The Attempt at a Solution
I think you gotta split this one in terms of axis.
∫(2yi + x2j) dx
Pretty lost on it.
Ahh just caught that. Replugged in the values, and still came out wrong.
Work:
Plugged in 90/(Sqr97*Sqr117) = .8448190756
Tan-1 (.84481....) = 40.191 degrees.
Plugged that into online homework and it was wrong apparently.
1. Homework Statement
2. Homework Equations
Tan θ=A.B/|A|*|B|
3. The Attempt at a Solution
A=4i-9j
B=9i-6j
A.B=-18
Magnitude of A = √97
Magnitude of B = √117
Solve that out using Cos-1 (-18/Sqr97*Sqr117) and I keep getting the wrong answer.
Come on guys :frown:. i just need to know how to find the tension and i'm good to go on part b to the end!
from what I understand, the only forces acting upon the rope are those of the rope itself and gravity. i used mv^2/r + mg and I got around 13.4. my online homework keeps telling me i'm...