Search results

  1. P

    T-butyl vs. isopropyl subsitutions

    Homework Statement T-butyl chloride can undergo substitution reaction to create C4H9OH, but isopropyl chloride cannot. Why is this? Homework Equations The Attempt at a Solution I'm guessing it has to do with the extra carbon. Maybe since it is a secondary halide, the substitution...
  2. P

    Substance decrease by factor of 100? (radioactivity)

    Homework Statement Radioactive iodine (131-I) has a half life of 8 days. How long does it take for iodine to be reduced by factor of 100? Homework Equations N(t)=N(o)e-kt k=ln100/t1/2 The Attempt at a Solution N(t)=N(o)e-kt N(t)/N(o)=e-ln(100/8)t Now I'm stuck. I would...
  3. P

    Principal Quantum number by size?

    Homework Statement What is the value of the principal quantum number for a hydrogen atom to have a size of one micron? Homework Equations r=(5.3x10-11)(n2) r=1x10-6/2=5x10-7 The Attempt at a Solution 5x10-7=(5.3x10-11)(n2) 97.1 = n How is this possible? lol Maybe it's more complicated...
  4. P

    What is electric field problem?

    Homework Statement Two uniform plates have a uniform charge density of 10 Coulombs/m2. The plates have dimensions of 0.6x0.6 m2 and are seperated by 2mm a) The electric field (V/m) between the two plates is given by E=1.13x1011 Q/A where Q is the charge in Coulombs on one plate and A is the...
  5. P

    Charge on each mass?

    Homework Statement Two equally charged 1g masses repel each other. The lower mass is held fixed. a)What is the charge on each mass for the Coulomb force to balance the gravitational force of the Earth on the upper mass? b)How many elecetrons does this rep? Homework Equations...
  6. P

    What are the resonant wavelengths?

    Homework Statement Consider pipe of lenght L. The pipe is closed at one end and open at the other allowing a standing wave where a node exists at the closed end and a max exists at the open end. a) what are the resonant wavelengths? b) If L=5, what is the lowest frequency? Homework...
  7. P

    How long should she wait?

    Homework Statement An orchestra wants to have a listener in front of a conductor hear notes at the same time, played by the violinist located next to the conductor and from a drummer located 33m further back. a) How long should the violinist wait before playing her note? (assuming drummer...
  8. P

    Another Momentum one, sorry

    Homework Statement A .5kg hockey puck moving at 2 m/sec strikes another puck with a mass of 1kg. The puck then travels at an angle of 60 degrees with a speed of .75m/sec with respect to the motion of the original puck. a) What is the final speed of the first puck? b) What is the final...
  9. P

    Kinetic E & Potential E Question

    Homework Statement A 55kg mass is projected vertically with and initial speed of 30m/sec a) what is original kinetic energy b) What is kinetic E after 4.5 seconds c) What is chg in gravitational potential E in these 4.5seconds? Homework Equations W=mv2/2 W=(m/2)(gt)2 W=mgh...
  10. P

    Niagra Falls Q

    Homework Statement Estimate E generated by water falling over Niagara falls in 5 day. Height = 150m Water flow =104m3/sec t=5x24x60x60=4320000sec Homework Equations P=W/t mgh=mv2/2 The Attempt at a Solution Work=mgh=m(9.8)(150) Time=432000seconds P=m(1470)/4320000 I just...
  11. P

    Object to lose weight

    Homework Statement How far above the earth must an object be in order to lose 30% of its weight? Homework Equations ma=Gm(Mearth)/r^2 a=v^2/r v=2pir/T The Attempt at a Solution I think the 30% lost weight would be the same as the earth's weight losing 30%. Therefore, I can put...
  12. P

    What does this tell you about how the moons were created?

    Homework Statement Two identical spaceships are sent to explore a planet with two moons. Each spaceship orbits one of the moons. a)The orbital radii are observed such that the spaceship have the same period. What is the relative mass of the two moons if the two radii differ by a factor of...
  13. P

    Centripetal Acceleration at Equator

    Homework Statement An individual standing at the equator: a)What is this individuals centripetal acceleration caused by the earths rotation? b)How fast would the earth need to spin in order for the centripetal acceleration to be equal to g? T=1 day radius of earth = 6.4x10^6 m...
  14. P

    Weird physics question

    Homework Statement A block, moving along a horizontal plank, is acted upon by a force of friction that is equal to 35% of the weight of the block. The block comes to rest from a speed of x m/s. Find x. Homework Equations v=u + at F=F1 + F2 The Attempt at a Solution I can't even attempt...
  15. P

    Another Centripetal Force Q

    Homework Statement A truck with a mass of 20000kg goes around a circular path with a speed of 50km/hr. If the radius is 105m. Calculate the centripetal force acting on the car. Homework Equations This is why I can't get the answer to this question. I don't know which equation to use. I'm...
  16. P

    Force question

    Homework Statement A 10kg mass has a force pointing in the east direction and another force pointing in the south direction 45 degrees from the east force |F1|=12 Nt, |F2|=19 Nt a)total force vector? b)mag of total force c)direction of total force Homework Equations F=F1 + F2...
  17. P

    Non-Horizontally launched Projectile

    Homework Statement A ball is thrown from the ground (height=0) with an initial speed Vo at an angle of 45 degrees a)when does ball start falling to earth b)what is balls max height c)How long does it take to hit the ground again? d)where does the ball hit the ground? Homework...
  18. P

    3D Motion

    Homework Statement A boat heading south initially with a speed of 10 m/s has a constant acceleration of a= (10,5,10) m/s^2 What is the velocity, speed, position and distance travelled after 30 minutes? u=10m/s a=(10,5,10) t=30 min = 1800 Homework Equations v = u + at The Attempt at a...
Top