# Search results for query: *

1. ### Block and Spring (Simple Harmonic Motion Problem)

I figured out what I did wrong in this situation... cos-1(0) could be either pi/2 or -pi/2, and because the motion is coming to the end of a complete cycle I should have used -pi/2. To answer your question, I determined the phase shift=phi by solving the position equation. I knew at t=0...
2. ### Block and Spring (Simple Harmonic Motion Problem)

Homework Statement At t = 0 a block with mass M = 5 kg moves with a velocity v = 2 m/s at position xo = -.33 m from the equilibrium position of the spring. The block is attached to a massless spring of spring constant k = 61.2 N/m and slides on a frictionless surface. At what time will the...
3. ### Area of the region bounded between two curves with integration by parts

My mistake was in the bounds, which should have been from 1 to 34. Thank you for your help!
4. ### Area of the region bounded between two curves with integration by parts

Homework Statement Find the area bounded between the two curves y=34ln(x) and y=xln(x) Homework Equations Integration by parts: \intudv= uv-\intvdu The Attempt at a Solution First I found the intersection points of the two equation to set the upper and lower bounds. The lower...
5. ### Volume of Cylindrical Shells: y = 4x - x^2, y = 3; about x = 1

nevermind, I've got it! sorry for my faulty answer and thank you for correcting my mistake.
6. ### Volume of Cylindrical Shells: y = 4x - x^2, y = 3; about x = 1

why would the limits of integration be from 1 to 3 if you are integrating with respect to the x axis?
7. ### Volume of Cylindrical Shells: y = 4x - x^2, y = 3; about x = 1

I think the mistake you are making is in the formula that you are integrating. It seems like you were thinking washers while using the shell equation. The general equation to use for the shell method is 2\pi\int R dx(dx can change depending on which variable you are integrating with respect...

all you have to do is multiply it to the two solutions so say the factored quadratic is (x-4)(x+4), so the solutions are 4 and -4. just multiply the rad5 to those two answers.
9. ### Help with classical mechanics question

Momentum is always conserved in a closed system-that is, if there are no external forces that could effect the situation. Hope that helps!
10. ### Kinematics Final Velocity Question

very happy to help:D
11. ### Kinematics Final Velocity Question

because the velocity is downward it is negative, as well as the acceleration. you can't interchange them. it is just important to note the direction of the velocity depending on the equation you decide to use!
12. ### Kinematics Final Velocity Question

also correct! acceleration is -9.8 m/s2. something to think about--what is the direction of the velocity?
13. ### Kinematics Final Velocity Question

exactly! 2 m/s would be the initial velocity.

15. ### Kinematics Final Velocity Question

Is the initial velocity 66 or 68 m/s? If it is 68 m/s, your answer is very close to mine---I'm sure just rounding differences. Just double check the problem.
16. ### Question involving tension

right on! very good.
17. ### Kinematics Final Velocity Question

This equation is fine to use, but you will have to solve for acceleration (you have the initial and final velocities, plus the time!) Once you solve for acceleration, you can solve for the displacement over time.
18. ### Conservation of Energy Possibly

k=spring constant so it is accounted for. the negative sign is correct, but you also have to take into consideration that you will be taking the square root of the magnitude of the work. the negative simply implies direction--the spring is being compressed.
19. ### Conservation of Energy Possibly

**solve for the x value where W=1/2kx^2! sorry that was not very clear
20. ### Conservation of Energy Possibly

okay here are my thoughts... you were right in thinking that this is a conservation of energy problem, or at least that is what I did too. we know that the work done by the spring is equal to 1/2kx2, and we also know that work is defined as force times distance. you can solve for the force of...
21. ### Conservation of Energy Possibly

i'm working on it so you know that someone has seen it!
22. ### Question involving tension

Think about Newton's 2nd law...draw a free body diagram of the situation. because they want the answer in variables, don't consider the magnitude of the acceleration!
23. ### Inclined plane w/ friction problem

this looks good to me!
24. ### Solving Exponential Equations SO CONFUSED ?

Don't distribute! Divide both sides by 3, leaving you with 5^x+1=5 and remember that 5=5^1
25. ### Solving Exponential Equations SO CONFUSED ?

Excellent explanation!
26. ### Solving Exponential Equations SO CONFUSED ?

Also-Because there are exponents involved, don't multiply the number outside of the parentheses inside of the parentheses!
27. ### Solving Exponential Equations SO CONFUSED ?

Okay! well, if the exponents have the same base (ie 2^x-1=2^6-x) then you can set the exponents equal to each other. For your problems, you will have to manipulate the bases to get them to be the same... for example if you have 2^x-4=8, that also equals 2^x-4=2^3, so then x-4=3.
28. ### Solving Exponential Equations SO CONFUSED ?

correction! 2(3^y-2) = 18 3^y-2=9 ln3^y-2=ln9 (y-2)ln3=ln9 y=(ln9)+2/ln3
29. ### Solving Exponential Equations SO CONFUSED ?

use natural logs to solve for the exponents! ie 2(3^y-2) = 18 3^y-2=9 ln3^y=ln9 yln3=ln9 y=ln9/ln3 all of them can be solved that way!
30. ### Finding distance using vector components

the beauty of unit vectors is that it already takes the angle into consideration! all you have to do in this case is add the i vectors with i vectors and js with js.
31. ### Finding distance using vector components

here's some reading for you to do that should help! http://www.physics.uoguelph.ca/tutorials/vectors/vectors.html
32. ### Isosceles Triangular Prism Related Rates Problem

oh! I differentiated much too early... thank you so much for your help!
33. ### Isosceles Triangular Prism Related Rates Problem

Right! I used the same equation I put before dv/dt=l(1/2b(dh/dt)+1/2h(db/dt)) and, differentiating b=5h, dv/dt=l(1/2b(dh/dt)+1/2h(5dh/dt)) Also, I really appreciate your help!
34. ### Isosceles Triangular Prism Related Rates Problem

Once I replaced the db/dt with the 5dh/dt and solved for the problem I got .4817 ft/min but that was incorrect. The equation I used was... 14=9(1/2*5(dh/dt)+1/2*(7/12)5(dh/dt)
35. ### The rate at which the coffee is cooling

Think Newton's Law of Cooling.
36. ### Isosceles Triangular Prism Related Rates Problem

That seems to be just what my problem is... I can't see the relationship between b and h. I tried setting up a triangle and solving for what b is equal to in terms of h but I am still getting the wrong answer. I used cos(theta)=(1/2b)/h, differentiated, and solved for what db/dt was equal to.
37. ### Isosceles Triangular Prism Related Rates Problem

Homework Statement A trough is 9 ft long and its ends have the shape of isosceles triangles that are 5 ft across at the top and have a height of 1 ft. If the trough is being filled with water at a rate of 14 ft3/min, how fast is the water level rising when the water is 7 inches deep? I...
38. ### Differentials word problem

genius...thank you!
39. ### Differentials word problem

Homework Statement Use differentials to estimate the amount of paint needed to apply a coat of paint 0.05 cm thick to a hemispherical dome with diameter 54 m. Homework Equations dy=dy/dx *dx Surface area of a hemishpere=2pi*r^2 The Attempt at a Solution dy=4pi*r dx dy=4pi*27...
40. ### Coefficient of friction of a ramp

Thank you so much for the help!
41. ### Coefficient of friction of a ramp

That is exactly as the problem is written, the only thing I forgot to include was that we are looking for the coefficient of friction. Sorry about that!
42. ### Coefficient of friction of a ramp

Homework Statement A student has two ramps, both of which are at an angle of 30o. Ramp 1 is frictionless and ramp 2 has friction. The student also has two blocks, one for each ramp. She pushes the blocks up the ramps with the same initial velocity. The block on ramp 2 only travels a...