Recent content by spl-083902

  1. spl-083902

    What causes drag on a stationary car?

    That's right, the forward acceleration of the car would have to be greater. However, you're still missing something. What would cause drag on a car at rest? If a rock is at rest on the ground does it have drag? Does a car parked in a garage have drag? Why would that answer change if the car...
  2. spl-083902

    What causes drag on a stationary car?

    Drag is velocity dependent, not acceleration dependent. Think about what is it that physically causes drag on a car. Also, remember that the way the car will ultimately move is going to be the direction of the net vector. So always check that it makes sense. If you're saying that your largest...
  3. spl-083902

    What causes drag on a stationary car?

    For the car problem, what is the drag on an object at rest? For the rocket, check to see if the sum of all your vectors makes sense, if they were all placed head to tail.
  4. spl-083902

    Finding a time-dependent vector

    How are you eliminating the constant from the equations? and why do you think you need 2 equations to solve it? I think you can do it with just 1
  5. spl-083902

    DISPLACEMENT-TIME graphs question

    I'm sure you know this equation v=\frac{d}{t} and just do it in sections
  6. spl-083902

    Will society ever get rid of Lookism?

    Having this as a factor in relationships is something I can live with. What bothers me is how it plays roles in things like job interviews. You can argue that someone who looks nice is probably a nicer person and will be better for morale in the workplace, etc... But those are logical arguments...
  7. spl-083902

    Identify the following motions as positive or negative accelerations

    Actually on second thought you should probably just treat it as positive. Getting a positive acceleration on an object traveling in the negative direction is still causing the object to slow down and I think the point of this problem is for you to call that negative acceleration. So for this...
  8. spl-083902

    Identify the following motions as positive or negative accelerations

    West is only negative if you define it to be so. It would be good practise to see how you get the same answers for this problem whether you take west to be negative or positive. You put N/A for relevant equations, but you could have put an equation relating acceleration to change in velocity...
  9. spl-083902

    How Long Does It Take for a Car to Stop with Friction After Engine Shutdown?

    Looks like you did it right. Other than writing 0= 30 +(-0.015)(t) = 2000sec which is technically wrong since 0 != 2000sec. You should put t=2000s on a separate line
  10. spl-083902

    Where did all the physics ladies go?

    I don't think there's anything wrong with bringing it up. I think it might seem like a taboo subject just because we are talking about a field that usually is viewed to have a lot of "smart people" in it, so subconsciously people might think you're talking about an intelligence difference when...
  11. spl-083902

    What are the steps to solve a work problem?

    This is one area of physics that I think gets easier when you get to more advanced levels, where such a procedure exists. But for basic physics I would say to try this. Just quickly ask yourself what is doing the work, and what is it doing the work on. Then just quickly think about W=F*d to...
  12. spl-083902

    Magnitude, 2D co-ordinates and Coulomb's Law

    r-hat (\hat{r}) is a unit vector. Unit vectors have a length of 1. In this way you can separate out the "magnitude" of a vector from its direction. So you can think of r-hat as a vector (of length 1) that points in the direction from the particle to where you want to measure the force at. Any...
  13. spl-083902

    Light waves and intereference patterns

    To understand this just find the probability distribution of a linear combination of wavefunctions passing through each slit: \Psi=R_{1}e^{i\theta_{1}}+R_{2}e^{i\theta_{2}} and find |\Psi|^{2} You should end up with R1^2 + R2^2 plus a cross term which exhibits the interference. Then to see why...
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