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  1. L

    Draw a ray diagram

    A converging lens has a focal length of 25cm. A 1.00cm tall object is placed 15.0cm in front of the lens. Find the image location and size, and describe it. Draw a ray diagram. Ok so I get 1/p + 1/q = 1/f rearranged for q=pf/p-f which equals -37.5, so the object is 37.5cm behind the lens. and...
  2. L

    Converging lens

    A converging lens has a focal length of 25cm. A 1.00cm tall object is placed 15.0cm in front of the lens. Find the image location and size, and describe it. Draw a ray diagram. Ok so I get 1/p + 1/q = 1/f rearranged for q=pf/p-f which equals -37.5, so the object is 37.5cm behind the...
  3. L

    How do you find the angle of polarization? What is the formula?

    How do you find the angle of polarization? What is the formula? Its not in my physics book and I looked online and couldn't find it.
  4. L

    Fraction Of The Intensity Incident

    Two Polaroid filters are initially crossed. The analyzer is rotated through an angle of 55.0 degrees. Find the fraction of the intensity incident on the polarizer which passes the analyzer. I used I1=1/2 Io I2= I1cos I2= 1/2 Io cos^2(theta) = 1/2 Io cos227.5° = .393 Io Is...
  5. L

    Calculate power produced in each bulb

    Given two light bulbs with the following ratings: 75.0W 120VAC and 100W 120VAC. They are connected in series across a potential difference of 120. VAC. Assuming that the operating resistances of the bulbs are not affectd by the series connection, calculate (a) the power produced in each bulb...
  6. L

    Use galvanometer

    A galvanometer of 90 ohms internal resistance has a full-scale current of 350. microA. Describe how to use this meter to make : (a) a 150 V voltmeter, and (b) a 10.0A ammeter So (a) Resistors must be connected in series with the galvanometer, R=4.29 x 10^5 ohms. (b) A shunt resistor must...
  7. L

    Repulsive force

    Find the repulsive force on two protons in the nucleus of an atom assuming they are separated by the minimum distance of 1.00 x 10^-15m. So F=k lq(1)l^2/ r^2 =8.99 x 10^9 (1.602 x 10 ^-19)^2/(1.00 x 10^15m) =230.7N Is this correct?
  8. L

    Melting ice

    How much ice could be melted by 320. grams of water at 68.0 degrees C? Would I us mL + mcT=0 for the equation, and do the latent heat of ice for the first part and water for the second?
  9. L

    Black body

    How many times more energy is emitted from a black body at 550. degrees C than at a room temperature of 22.0 degrees C. So I know that a double in temperature increases energy by 2^4=16 so would I just do 25^4=390625 for this problem?
  10. L

    Linear Expansion

    A 215.m steel bridge has an expansion joint of 18.0cm at one end at -15.0 degrees C. At what temperature would the joint be closed? I would use the equation Change in L=L(alpha)T But would the L equal zero since the joint is closed?
  11. L

    Temperature change boiling water

    An iron cylinder is heated to 100.degrees C in boiling water ant then transferred to 145.0 grams of water in a 70.0 gram copper calorimeter at 20.0 degrees C. If the final temperature is 25.2 degrees C find the mass of iron used. Would I use mL(Boiling water)+mcT(water)+mcT(coper...
  12. L

    Calculate the ideal (Carnot) efficiency of a heat engine

    Calculate the ideal (Carnot) efficiency of a heat engine operating between 23.0 degrees and 515 degrees. How much heat would be rejected by the engine if 1.00 x 10^6 calories were taken from the high temperature resivoir. Would you just use e=1-(T(c)/T(H))? And for the second part i don't...
  13. L

    Change in Internal Energy

    930.J of work are done by an insulated system that absorbs 3.35Kcal of heat. What is the change in the internal energy of the system? Ok so I don't quite understand this. I know that U=Q-W. but I do I just do 3.35Kcal minus W? This just doesn't seem right.
  14. L

    Sound in phase

    Two speakers produce a 162Hz sound in phase. If an intensity minimum is located 3.75m from the nearer speaker, find the distance to the further speaker if the speed of sound in the air is 345m/s. Would it go like this d(1)-d(2)/wavelength=phase difference/2pi x-3.75/2.13=1/2pi x=4.09m...
  15. L

    Shock wave

    What is the shock wave cone half-angle for a supersonic airplane flying at Mach 2.30? Would you use Mach=1/sin(theta) and then divide by 2 to get the half angle? So 2.30=1/sin(theta)=12.9 degrees
  16. L

    Intensity physics homework

    Two speakers produce a 180Hz sound in phase. If an intensity is located 2.10m from the nearer spearker, find the distance to the further speaker if the speed of sound in the air is 345m/s. I don't understand exactly what this problem is asking for, and I can't find an equation relating these...
  17. L

    Finding harmonics

    In finding harmonics do you just multiply the harmonic number times the frequency? Find the first four harmonics when f=343Hz would be f1=343Hz, f2=686Hz, f3=1029Hz, and f4=1372Hz. This just seems too easy.
  18. L

    Find its signal wavelength

    A FM radio station has a frequency of 106.5MHz. Find its signal wavelength. I am guessing that you would use the speed of sound in this problem correct me if I am wrong. So Wavelength=v/f =343/1.065*10^8 =3.22*10^-6m Is this right?
  19. L

    Period, velocity, acceleration of a spring

    A .390kg mass is suspended from a spring. A force of 1.00N stretches it an additional 35.0mm. Find the force constant of the spring, the period of the motion which results when the mass is released, the maximum acceleration, and the maximum velocity. Ok so the force constant is F=ky...
  20. L

    Find load with jack and piston

    A hydraulic jack has a pump piston of diameter 0.650cm, and a load piston of 4.40cm. Find the load which can be lifted if a force of 500.N is exerted on the pump piston. Would you use the equation Fd=F(2)d(2)? So (0.00650m)(500.N)=F(.0440m) =73.9N
  21. L

    Ballistic pendulum

    a 4.00g bullet moving at 380m/s embeds itself in a wood block of mass 2996g suspended as a ballistic pendulum find: (a)the initial velocity of the block after the impact, and (b) how high the block rises. I did it this way can someone tell me if i did it right (a)m(1)v(1i) + m(2)v(2i) =...
  22. L

    Find the x component for the force parallel using xcos

    A block weighing 95.0 lbs is on a 34.5 degree plane. Find the force parallel to the plane, the acceleration if there is no friction, the coefficient of friction if the object is just at the point of sliding, and the acceleration if coefficient of sliding friction is .350. Do you find the x...
  23. L

    Crate sliding on a flatbed truck

    A crate of oranges weighing 180N rests on a flatbet truck 2.0m from the back of the truck. The coefficients of friction between the crate and the bed are us=0.30 and uk=0.20. The truck drives on a straight, level highway at a constant 8.0 m/s. (a) What is the force of friction acting on the...
  24. L

    Help with tension physics

    A pulley is attached to the ceiling. Spring scale A is attached to the wall and a rope runs horizontally form it and over the pulley. The same rope is then attached to a spring scale B. On the other side of scale B hangs a 120 N weight. What are the readings of the two scales A and B? The...
  25. L

    Find normal and friction force on a crate full with artichokes

    Help please! A crate full of artichokes rests on a ramp that is inclined 10.0 degrees above the horizpntal. Give the direction of the normal force and the friction force acting on the crate in each of these situations. a) The crate is at rest. b) The crate is being pushed and is sliding up...
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    Physics help on plane and equilibrium

    an airplane is cruising along in a horizontal level flight at a constant velocity, heading due west. (a) If the weight of the plane is 2.6 x 10^4 N what is the net force on the plane? (b) with what force does the air push upward on the plane? (c) Is the plane in equilibrium? If so, what kind of...
  27. L

    Here's another

    The mass of the moon is 0.0123 times that of the Earth. A spaceship is traveling along a line connecting the centers of the Earth and Moon. At what distance from the Earth does the spaceship find the gravitational pull of the Earth equal in magnitude to that of the Moon? Express your answer...
  28. L

    How many kN are in a Kg?

    I have a question how many kN are in a Kg??? I have looked and cannot find it.
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