# Search results

1. ### Better Thermal Insulator for Glass - Neoprene or Silicone?

I am looking to improve the thermal insulation on one of my favorite glass mugs. I am choosing between a silicone glove or a neoprene wrap. What is the difference between a silicone baking mat and silicone rubber? Does silicone or neoprene have better thermal insulation?
2. ### Does an Induction Cooking Pan Need to be Completely Ferrous?

Do you think that a ferrous plate at the bottom would suffice though? Or would a completely ferrous pan be significantly better?
3. ### Does an Induction Cooking Pan Need to be Completely Ferrous?

I ask, "Does a ferrous pan for Induction Cooking need to be Completely Ferrous?" In other words, could just the bottom of the pan be a ferrous material for good inductive heat induction? Could I have a ferrous bottom, and ferrous sides that turn to a non-ferrous material after a couple...
4. ### Question on Surface Integral and Flux

Could I use, (3,-1,0)x(0,0,-1)?
5. ### Question on Surface Integral and Flux

Alright, so the corss product of two vectors will give me a vector that is perpendicular to the plane (which is in the direction that I want). I'm not sure what these vectors would be? How do I know what vectors to cross?
6. ### Question on Surface Integral and Flux

Would I compare triangles in the xy-plane?
7. ### Question on Surface Integral and Flux

Homework Statement I have a coordinate system, (x,y,z). There is a uniform-magnetic-field of 2.0 T that exists along the direction of the y-axis. There is a rectangular plane bounded by the points (3,0,0),(0,1,0),(0,1,1),(3,0,1). Calculate how much flux is traveling through the rectangular...
8. ### Finding Omega and Zeta from a Magnitude and Phase Plot

Yes, I am assuming that the AFM cantilever is being modeled as a second order system. With the cantilever tune, the phase curve is set to 90° of the resonant frequency. So would I be close enough in estimating that the natural frequency is 72.7 kHz?
9. ### Finding Omega and Zeta from a Magnitude and Phase Plot

I was able to calculate the value for the damping ratio; but I am having trouble finding the value of the natural frequency. Any ideas on how to solve for the natural frequency?
10. ### Finding Omega and Zeta from a Magnitude and Phase Plot

Could you elaborate? Where does this -3dB bandwidth come from? Is Q inversely related to the damping ratio, ζ? Thanks for your help.
11. ### Finding Omega and Zeta from a Magnitude and Phase Plot

Homework Statement I've been asked to estimate ωn and ζ from the magnitude and phase plot of an atomic force microscope. The magnitude and phase plot is attached. Does anyone know how to solve for these values?
12. ### Calculating Transformer Input Voltage?

The load is 1.5Ω, and Xm is also in Ω.
13. ### Calculating Transformer Input Voltage?

Homework Statement A 2400/240-V, 60-Hz transformer has the following parameters in the equivalent circuit of Figure 6.5: the high-side leakage impedance is (1.2+j2.0)Ω, the low-side leakage impedance is (0.012+j.02)Ω, and Xm at the high-side is 1800 . Neglect Rhe. Calculate the input voltage...
14. ### Electric Potential Question

Homework Statement Which of the following statements about the electric potential inside a metal object are correct? Check all that apply. The potential at any point inside a metal at equilibrium is equal to the potential at the surface, which may be nonzero. The potential is the same...
15. ### Which of the following

Which of the following... Homework Statement In a collision between an electron and a hydrogen atom, it is useful to select both objects as the system because: A. The total momentum of the system does not change during the collision B. The forces the objects exert on each other are...
16. ### Finding Kinetic Energy of a Collision

Homework Statement A 900 kg car moving east at 31 m/s runs head-on into a 2800 kg truck moving west at 15 m/s. The vehicles stick together. Use the concept of the center-of-momentum frame to determine how much kinetic energy is lost. Homework Equations Kf= Ki(car) + Ki(truck) K=...
17. ### Rotational Velocity Problem

That's not the equation? Then what equation would I use to represent the rod with moment of inertia?
18. ### Rotational Velocity Problem

Moment of Inertia= mr^2. Sorry.
19. ### Rotational Velocity Problem

Homework Statement A thin uniform-density rod whose mass is 3.8 kg and whose length is 3.0 m rotates around an axis perpendicular to the rod, with angular speed 34 radians/s. Its center moves with a speed of 10 m/s. (a) What is its rotational kinetic energy? (b) What is its total kinetic...
20. ### Vertical Spring Potential Energy?

Homework Statement Say I have a vertical spring, with a mass attached to the bottom of the spring, and the spring is attached to the ceiling. Say I push up on the mass compressing the spring, and then I release the spring from rest. Do I need to take into account the gravitational...
21. ### Fun theory physics question

Hi, I was wondering this question: Why does U=mgh and U=Gm1m/R come out to similar values even when their equations are completely different? Thanks
22. ### Classic Football Kick Problem

You could square both sides, and then we can work it out from there?
23. ### Classic Football Kick Problem

Are there any sin and cosine laws that would help, like the square of sin added to the square of cosine equalling one?
24. ### Classic Football Kick Problem

hmm. what did you come out with?
25. ### Classic Football Kick Problem

Ok i'll, as well.
26. ### Classic Football Kick Problem

I don't see what you're getting at. I know there are these two equations, I need to solve a variable deltat to get one variable left. After I try to do that step, I get a ridiculous equation that I need to solve for theta. Is there any other process of doing this problem?
27. ### Classic Football Kick Problem

I attempted to solve for deltat, but when I plugged delta t from the 2nd equation into the first equation i get a long equation with costheta- costhetasintheta. I'm confused
28. ### Classic Football Kick Problem

the higher angle would be when the ball strikes the top of the post.
29. ### Classic Football Kick Problem

Because the problem does not supply deltat, where should that number come from? 54m/27m/s= 2s?
30. ### Classic Football Kick Problem

my answers don't seem to be working. I get for the largest angle possible: 54= 27^2sin(theta)^2/ (9.8) = .8520=sintheta= 58 degrees. would that be correct for the larger angle?
31. ### Classic Football Kick Problem

u stands for velocity, correct? and how do I differentiate between the largeer and smaller angles?
32. ### Classic Football Kick Problem

hmm. I'm still confused. Would I do 54= 27sin(theta)*deltat + .5(-9.8)deltat and then solve for theta?
33. ### Classic Football Kick Problem

Homework Statement A football kicker can give the ball an initial speed of 27 m/s. He is 54 m from the goalpost which has a crossbar 3.37 m high. (a) What is the largest angle of elevation that he can kick the football and score a field goal? (b) What is the smaller angle of elevation that...

35. ### Position of an object after a certain amount of time?

So, the velocity would be <0,0,-5> since it is in the -z direction?
36. ### Position of an object after a certain amount of time?

Ok, xf = xi + vi*t + 0.5*a*t^2 xf = <0,0,0>m + <0,0,5>*20 + 0.5*(<0,0,-30>N/200kg)*(20s^2)
37. ### Position of an object after a certain amount of time?

So I'll use: deltax = vi*t + 0.5*a*t^2. I plug in the proper values, and I don't get the correct answer. I am unsure of where I am going wrong. The initial position is, <0,0,0>, so I don't need to worry about that.
38. ### Position of an object after a certain amount of time?

Homework Statement Your location is at the origin. When an object passes you, it is traveling 5 m/s in the −z direction. If the object's mass is 200 kg, and the net force on the object remains constant at ‹ 0, 0, −30 › N, what is the position of the object 20 seconds after it passes you...
39. ### How to Change a Horizontal Vector to Move in a 45 degree angle

Ok, So the x-component is 1e7cos(45), where the y-component is 1e7sin(45), so the hypotenuse is the vector that makes up both of these components, which allows the object to move in the direction that is 45 degrees from the horizontal. Is that a decent understanding? Thanks for your help.
40. ### How to Change a Horizontal Vector to Move in a 45 degree angle

Where do you get the formula: vx = speed * sin (45)? Thanks.
41. ### How to Change a Horizontal Vector to Move in a 45 degree angle

Ok, I get it, and I got it working. Thanks for your help.
42. ### How to Change a Horizontal Vector to Move in a 45 degree angle

Homework Statement I am using vPython, and object moves in a +x direction with a vector of <1e7,0,0>m. I need to now change the vector so that it now moves in the same +x direction, but also moving in the northeast direction at an angle of 45 degrees. The Attempt at a Solution I...
43. ### Basic Concept Physics Question

Homework Statement An object is moving in the +z direction. Which, if any, of the following statements do you know must be false? Check all that apply. 1. velocity of z is zero. 2. The net force on the object is in the -z direction. 3. The net force on the object is zero. 4. The net...
44. ### INtegral Problem

Homework Statement Integral of (sec(10x)^2)*(tan(10x)^6)dx Homework Equations The Attempt at a Solution The powers are throwing me off a little bit. I realize that the derivative of tan is sec^2, bt how will that help me with this problem?
45. ### Double Integral Problem Help

Homework Statement ∫4to5 ∫1to2 (1x + y)−2 dy dx The Attempt at a Solution I am confused about what to do with this negative 2. Any ideas?
46. ### Tangent Plane Problem- Simple Question

Duh. Thank you!
47. ### Tangent Plane Problem- Simple Question

Homework Statement Consider the function f(x,y) = 4-x^2+3y^2 + y. Let S be the surface described by the equation z= f(x,y) where f(x,y) is given above. Find an equation for the plane tangent to S at the point (-1,0,3) The Attempt at a Solution Ok, SO i solved for the gradient of F...
48. ### Velocity and Acceleration Vector Problem

Ok, I understand. Than you cepheid and Mark44 for helping me visualizing this problem! Thanks again! Loppyfoot
49. ### Velocity and Acceleration Vector Problem

any ideas? Basically, I'm stuck on the problem: For what values of t (if any) exist when the vector <1,2t,3t^2> is parallel to <0,2,6t>. I know <0,2,6t>= k <1,2t,3t^2>. What do I do next?
50. ### Velocity and Acceleration Vector Problem

COmputationally I feel like i am not getting anywhere. A=kv So , <0,2,6t> = k<1,2t,3t2> I get 0=k ; 2=2kt ; 6t=3t2k. Where should I go from here? Should I solve for k, because I tried that and I am going in circles...