Recent content by herbally

  1. H

    How much work is done by inflating a balloon?

    When I integrate the expression for pressure in terms of volume, I get an answer that is close to the correct answer but still off by a few thousand joules. I think my expression is wrong. I took the equation for volume of a sphere and solved it for diameter. Then I took that solution and...
  2. H

    How much work is done by inflating a balloon?

    Not sure but tend to think it's D1.
  3. H

    How much work is done by inflating a balloon?

    I realize that pressure and volume are changing. I assume that I need an expression for pressure in terms of volume. Since the given expression for pressure is in terms of diameter, I solved the equation for volume of a sphere for diameter, but, plugging that into the given expression for...
  4. H

    How much work is done by inflating a balloon?

    Kind of stuck. Not sure where to go from here.
  5. H

    How much work is done by inflating a balloon?

    You're right. Doesn't make much sense since the pressure would get smaller as diameter increases. Back to the drawing board.
  6. H

    How much work is done by inflating a balloon?

    The last term should have been 1600/D2. Sorry.
  7. H

    How much work is done by inflating a balloon?

    Heat capacity has units of J/g*K. I plugged 100 kPa in for P0, and 400 kPa for P and solved for C yielding a value of 1600 kPa. So then I plugged those values into the given expression and simplified yielding: P = 100 kPa + 1600 kPa/D - 1600 kPa/D So I guess I need this expression...
  8. H

    How much work is done by inflating a balloon?

    From the given expression, C should be in Pascals.
  9. H

    How much work is done by inflating a balloon?

    Not real sure how to interpret the problem there. I know the initial pressure in the tank is 1MPa and that the pressure added to the balloon is 100kPa, but I assume that P0 is the pressure when the balloon becomes spherical. Am I misinterpreting? EDIT: Just realized that I calculated n0...
  10. H

    How much work is done by inflating a balloon?

    Temperature is constant at 20°C. P0 = ? V0 = .5236 M3 n0 = 21.49 mol Pf = 400kPa Vf = 33.51 m3 nf = 5502 mol My inclination is that I should back-solve for P0 using the given expression, but I don't know what C is. Heat capacity is my only thought, but neither pressure or volume is...
  11. H

    How much work is done by inflating a balloon?

    Homework Statement An initially deflated and flat balloon is connected by a valve to a storage tank containing helium gas at 1 MPa at ambient temperature of 20°C. The valve is opened and the balloon is inflated at constant pressure of 100 kPa (atmospheric pressure) until it becomes...
  12. H

    Light ray passing thru plastic block

    I solved Snell's law for sin(θ2) which yielded n1sin(θ1)/n2. I set that equal to n2/n1. Then I solved for n2 which gave me n2=+-n1√sin(θ1). When I solve I get some value like .98755 which is less than one making it obviously incorrect.
  13. H

    Light ray passing thru plastic block

    Homework Statement A light ray passes downward into a block of transparent plastic with an angle of incidence of θ1 = 77.7°. If total internal reflection is to occur when the light strikes the left edge of the block at interface B, what is the index of refraction of the plastic? Homework...
  14. H

    Impulse-steel ball dropped on steel slab

    WOW. NM. I'm rum-dumb at this point. I got it. Thanks a ton.
  15. H

    Impulse-steel ball dropped on steel slab

    Naturally the initial velocity is negative. I'm failing to see the correlation. Then again, I've been doing physics for about 3 hours straight so all the numbers are beginning to run together. Perhaps another nudge? Thanks.
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