Recent content by EmilyHopkins

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    Finding the unknown cordinates of a point on a vector

    Wouldn't that just introduce another unknown variable which would require us to have 2 equations in order to solve. I thought this route already but didn't bother going this way since I don't know the ratio, and hence the value of k.
  2. E

    Finding the unknown cordinates of a point on a vector

    Well if AP and PB are parallel then their cross product is 0. 0 = AP X PB 0= ((t -1)i + (t-3)j) X (( T-7)i + tj) 0 = - (t-3)(t-7)k + (t-1)t k 0 = (3-t)(t-7) k + (t-1)tk 0= (3t -t^2-21+7t)k + (t-1)tk 0= (10t -t^2 -21)k + (t-1)tk 0= (10t -t^2 -21)k +(t^2 - t)k 0= (9t -21)k 9t-21=0 9t=21 t= 7/3
  3. E

    Finding the unknown cordinates of a point on a vector

    Relative to the origin O, the position vectors of two points A and B are (1,4) and (7,1) respectively. Give that the point P (t,t+1) is on AB find 1) AP and BP in terms of t 2) Find the value of t and hence the ratio AP:PBSolution: 1) AP= (-i - 4 j) + ti + (t+1)J = (t-1)i + (t-3)j BP=...
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    Dot Product Proof: Prove |a|^2 = 2|b|^2

    I'm assuming a and b are two non-parallel arbitrary vectors, as the question never specified what their relationship was. The diagram was used to visualize and help solve the second part of the question where they stated that if the parallelogram OPQR was a square, show by using two scalar...
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    Dot Product Proof: Prove |a|^2 = 2|b|^2

    Homework Statement The point P and Q have postion vectors a + b, and 3a - 2b respectively, relative to the origin O.Given that OPQR is a parallelogram express the vector PQ and PR in terms of a and b. By evaluating two scalar products show that if OPQR is a square then |a |2 = 2 |b |2 The...
  6. E

    How Do You Calculate the Enthalpy Change from Ethyne to Ethane?

    Calculate the standard enthalpy of ethyne C2H2 + 2H2 -------> C2H6 Assume the following mean bond energies C\equivC = 813 KJ mole-1 C - C = 364 KJ mole-1 C - H = 413 KJ mole -1 H - H = 436 KJ mole -1 Attempted Solution: Bonds broken 1 C\equivC = 813 KJ mole-1 ( 813 KJ...
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    How Much Man-Made Junk is on the Moon After 43 Years and Counting?

    Interesting what about if the moon was destroyed by weapons from earth. The gravitational biding energy of the moon is 1.245×10^29. The largest nuclear bomb detonated was Tsar bomb, which only had around 10^17 joules. So You would need roughly 1,000,000,000,000 of them. Say if we had the...
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    How Much Man-Made Junk is on the Moon After 43 Years and Counting?

    What would happen to the Earth's momentum theoretically speaking if the moon was destroyed by some outside body such as a asteroid ?
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