1. Chemistry Please :/

    When a metal was exposed to light at a frequency of 4.26× 1015 s–1, electrons were emitted with a kinetic energy of 4.50× 10–19 J. What is the maximum number of electrons that could be ejected from this metal by a burst of light (at some other
  2. Chemistry #13

    When a metal was exposed to light at a frequency of 4.26× 1015 s–1, electrons were emitted with a kinetic energy of 4.50× 10–19 J. What is the maximum number of electrons that could be ejected from this metal by a burst of light (at some other
  3. Chemistry

    To resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object. What kinetic energy must the electrons have in order to resolve a protein molecule that is 5.40 nm in diameter? Take the mass of an
  4. Earth Science

    Why is it generally warmer in a rural area than in an urban area? I have a question: How does the earth's surface heat up or cool down? My answer: the sun heats up the earth darker surfaces are warmer than cooler surfaces. Please help.
  5. PHYSIC

    1)What must be the orbital speed of a satellite in a circular orbit 740 above the surface of the earth? 2)What is the period of revolution of a satellite with mass that orbits the earth in a circular path of radius 8000 (about 1630 above the surface of the
  6. Physics

    A car with its passengers have a total mass of 4200kg .the car is travelling along a horizontal road when it moves ,it experiences a forward driving force of magnitude F newtons and a constant resistance force(opposite to driving force)of 850N a)what is
  7. physics

    How much additional energy is needed to fire a 7.2 × 10^2 kg weather monitor on the earth’s surface to a height of 120 km above the earth? (rE = 6.38 × 10^6 m, ME = 5.98 × 10^24 kg) Assume that the weather monitor rises to that height, stops, and
  8. Science

    A satellite orbiting at an elevation of 3200 km does what a) Stays beyond the earth's gravity, which is why it stays up there. B) in an elliptical orbit, since its speed is less than the escape velocity. C) Falling toward earth with an acceleration equal
  9. Physics

    a cross country runner runs 3km due east, 5km due south and 8km south west. what is the runners final displacement?
  10. U.S history slavery in the colonial south

    "how did the increasing complexity of the colonial south change the relationships between rich, and poor,black, red, and white, free and unfree?
  11. College Physics

    Four masses are positioned at the corners of a rectangle, as indicated in the figure below (not to scale). x 1kg------2kg | | | |y 3kg------4kg (a)Find the MAGNITUDE and DIRECTION of the net force acting on the 2.0 kg mass if x = 0.20 m and y = 0.11 m.
  12. south carolina history

    how did the french and indian war benefit south carolina’s economy please help me
  13. Physics-mechanics

    A 1.0 kg mass weighs 9.8 N on Earth's surface, and the radius of the Earth is roughly 6.4 x 10^6 m. Calculate the average density of Earth. (Show how you would calculate for density; don't just give the answer because L wan't to understand how you arrived
  14. Physics

    The mean radius of the Earth is R=6.38x10^6m. At what distance above the Earth's surface will the acceleration of gravity be 4.905m/s^2? F_g=(Gmme)/r^2 4.905=6.67x10^-11(5.98x10^24)/r^2 The mass cancel out so that is how I got the above answer. r=9017663m
  15. Calculus 2

    how do I find the fluid force of a vertical semicircle that has been divided into three equal sectors of 60 degrees each. I know what the equation to find the fluid force for the whole semicircle is. but how do I find L(y) for each semicircle.
  16. science Help 911!!

    Sodium chloride is formed when atoms lose and gain electrons. Carbon monoxide is formed when atoms share electrons. In both substances, atoms are held together by? A. Ionic bond B. chemical bond C. atomic mass D. proton Is the answer D? Your grandson can
  17. Physics Classical Mechanics

    A person of mass m2= 85.0 kg is standing on a rung, one third of the way up a ladder of length d= 4.0 m. The mass of the ladder is m1= 15.0 kg, uniformly distributed. The ladder is initially inclined at an angle θ= 40.0∘ with respect to the
  18. Chemisrty

    Why does ionization energy tend to increase as you move across a period? As you move across a period, you add a proton in the nucleus and an electron in the outer shell. Ther greater number of protons causes a stronger pull on the electrons. The electrons
  19. physics

    find the average of a block being propelled propelled by an elastic band. We know it is uniform acceleration. my attempt on this problem Measure the force applied of elastic band with a newton scale. The more you strecth the farther the distance the block
  20. physics

    A 2-kg block rests on a wall that is 3 m tall. What is the gravitational potential energy of the block? The force of gravity on Earth (g) is equal to 9.8 m/s2.
  21. Physics

    Calculate the force of the Earths gravity on a spacecraft 12,800 km (2 earth radii) above the Earths surface if its mass is 1350 kg?
  22. Electrochem

    An electrolytic cell produces aluminum from Al2O3 at the rate of ten kilograms a day. Assuming a yield of 100% a) how many moles of electrons must pass through the cell in one day? b) how many amperes are passing through the cell? c) how many moles of
  23. Physics

    If the mass of a planet is 0.571 times that of the Earth and its radius is 0.787 times that of the Earth, estimate the gravitational field g at the surface of the planet. The gravitational acceleration on Earth is 9.8 m/s2. Answer in units of m/s2
  24. earth

    The quantity of radiation received by earth from the sun is 1.4 kW / m2. Assuming that sun is an ideal radiator, calculate the surface temperature of the sun. The ratio of the radius of earth's orbit to the radius of the sun is 216.
  25. Physics

    If the mass of a planet is 0.103 times that of the Earth and its radius is 0.592 times that of the Earth, estimate the gravitational field g at the surface of the planet. The gravitational acceleration on Earth is 9.8 m/s2. Answer in units of m/s2
  26. physics

    A duck flies south at a constant speed of 20 m/s. A man stands 30 meters below the duck, he fires a shot upward at an initial velocity of 30 m/s. Half a second later the duck instantly commences a constant acceleration forward of 16 meters/sec^2. How far
  27. phys

    a spaceship travels with a speed of 0.7c as it passes by the Earth on its way to a distant star. The pilot of the spaceship measures the length of the moving ship as 50m. Determine its length as measured by a person on Earth. Answer in units of m. for this
  28. phys

    a spaceship travels with a speed of 0.7c as it passes by the Earth on its way to a distant star. The pilot of the spaceship measures the length of the moving ship as 50m. Determine its length as measured by a person on Earth. Answer in units of m. for this
  29. drbob222,math

    Am going correct with this one. It is estimated that the Earth is losing 4000 species of plants and animals every year. If S represents the number of species living last year, how many species are on Earth this year? S-4000=1 S=1+4000 S=4001 of species we
  30. calculus

    A man starts walking north at 2ft/s from a point P. Twenty-five seconds later a woman starts walking south at 3ft/s from a point 400ft due east of P. At what rate are the people moving apart 50 seconds after the woman starts walking? Do not include units
  31. Physics

    A motorcycle has a constant speed of 24.0 m/s as it passes over the top of a hill whose radius of curvature is 129 m. The mass of the motorcycle and driver is 330 kg. Find the magnitude of (a) the centripetal force and (b) the normal force that acts on the
  32. Physics

    A force of magnitude 7.50 {\rm N} pushes three boxes with masses m_1 = 1.30\,{\rm{kg}},m_2 = 3.20\,{\rm{kg}}, and m_3 = 4.90\,{\rm{kg}}, as shown in the figure(Figure 1) . (Ignore friction.) Find the magnitude of the contact force between boxes 1 and 2,
  33. Physics

    A 6.80 x 10^4 kg space shuttle moving at 7.90 x 10^4 m/s reenters the earth's atmosphere 80.0 km above the earth's surface. What is the shuttle's total mechanical energy with respect to earth's surface? I know the answer is E= 2.173 x 10^12J But I don't
  34. science

    the moon's gravity is about one-sixth the gravity on earth. mar's gravity is about one half the gravity on earth. make a bar graph that shows your weight (95 lbs) in newtons on earth, moon, and on mars. A newton is equal to about one quarter of a pound.
  35. Phyiscs

    A satellite circles the earth in an orbit whose radius is 2.07 times the earth's radius. The earth's mass is 5.98 x 1024 kg, and its radius is 6.38 x 106 m. What is the period of the satellite?
  36. physics

    A satellite circles the earth in an orbit whose radius is 2.01 times the earth's radius. The earth's mass is 5.98 x 1024 kg, and its radius is 6.38 x 106 m. What is the period of the satellite?
  37. physics

    A proton travels to the east at 3.5*10⁶ m/s as it enters a region of uniform magnetic field. The magnitude of the magnetic field is 0.15 T and its direction is 30° north of east. Find the magnitude of the force on the proton at the moment it enters the
  38. geography

    1. What gulf is north of Somalia and south of Yemen? The Gulf of Aden 2. What is the capital of Trinidad and Tobago? Port of Spain 3. What large river in Eastern Europe passes through Vienna, Austria, and Budapest, Hungary? The Danube River 4. Along what
  39. geography

    The Beaufort Sea touches what two North American countries? Canada and the United States 2. Are there any states located south of 25 degrees N latitude? If so, which one(s)? Yes, Hawaii. 3. What line of latitude falls halfway between the Tropics of
  40. Algebra

    A train leaves Danville Junction and travels north at a speed of 75 km/h. Two hours later, a second train leaves on a parallel track and travels north at 125 km/h. How far from the station will they meet? I have no idea what the system of equations would
  41. World Geography

    REVIEW 1.How do lines of latitude and longitude help geographers study Earth? A. These lines show geographers the direction of Earth’s rotation around the sun. B. These lines help geographers see the difference between oceans and landforms on Earth’s
  42. science

    find the gravitational force exerted by the sun on a 70 kg man located at the earth's equator a)at noon when the man is closest to the sun. b)at midnight when he is futherst from the sun. c)calculate the diferrence in gravitational acceleration due to the
  43. History

    President Andrew Jackson relocated Native American tribes living in the South because he believed that A.Native Americans would be more prosperious in the west B.US Citizens living in the South wanted Native American lands C.Native Americans needed to be
  44. Honors Trig.

    A plane is flying at a speed and direction of 550 mph, 25 degrees north of west. There is a wind of 28 mph, at an angle of 19 degrees south of the east direction. How fast is the plane actually flying? What direction is the plane traveling?
  45. Physics

    A jogger runs 145m. in a direction 20.0 degrees east of north (displacement of vector A) and then 105m. in a direction 35.0 degrees south of east (displacement of vector B). Using components, determine the magnitude and direction of the resultant vector C
  46. chemistry

    I want to have a deep insigth to my problem i.e. I know that bonds between atoms(of different or same elements)to be formed are based on no. of electrons less in octet or duplet(say O2, each O atom has two electrons less in octet thus forms two bonds).But
  47. Physics

    1. The efficiency of a squeaky pulley system is 73 percent. The pulleys are used to raise a mass to a certain height. What force is exerted on the machine if a rope is pulled 18.0 m in order to raise a 58 kg mass a height of 3.0 m? So to find the force
  48. Chemistry

    A single 4p orbital can hold how many electrons? i got 6 is that correct or no? Chemistry - Anonymous, Friday, September 10, 2010 at 2:52am "That is correct! px, py and pz (2 electrons in each) " since it's asking about a SINGLE 4p orbital would it be 2? i
  49. physics

    I need only part c Mars orbits the Sun at a mean distance of 228 million km, in a period of 687 days. The Earth orbits at a mean distance of 149.6 million km in a period of 365.26 days. All answers should be in the range (0, 2pi) a) Suppose Earth and Mars
  50. physics

    Only need help with part c Mars orbits the Sun at a mean distance of 228 million km, in a period of 687 days. The Earth orbits at a mean distance of 149.6 million km in a period of 365.26 days. All answers should be in the range (0, 2pi) a) Suppose Earth
  51. physics

    I need only part c Mars orbits the Sun at a mean distance of 228 million km, in a period of 687 days. The Earth orbits at a mean distance of 149.6 million km in a period of 365.26 days. All answers should be in the range (0, 2pi) a) Suppose Earth and Mars
  52. Math

    I have two questions that I need help with. 1. Angle of Depression: A Global Positioning System satellite orbits 12,500 miles above Earth's surface. Find the angle of depression from the satellite to the horizon. Assume the radius of Earth is 4000 miles.
  53. physics ..PLEASE HELP ASSIGN DUE SOON :(

    Forces of 11.1N north, 19.9N east, and 14.0N south are simultaneously applied to a 3.62kg mass as it rests on an air table. What is the magnitude of its acceleration? I already did this part and i got 5.56 m/s^2 BUT PLEASE HELP ME WITH part b!! b)What is
  54. earth

    The acceleration due to gravity on planet X is one fifth that on the surface of the earth. If it takes 4.6 s for an object to fall a certain distance from rest on earth, how long would it take to fall the same distance on planet X? Answer in units of s
  55. Physics

    A plumb bob does not hang exactly along a line directed to the center of the Earth's rotation. How much does the plumb bob deviate from a radial line at 38.5° north latitude? I got my answer to be 0.122288439 deg but it was incorrect. I used theta= a(sin
  56. Physics

    Determine the magnitude and direction of the total electric force on the +q charge by the +Q and -Q charges respectively. it should express and algebraic expression using Q,q,x,d and fundamental constants. -- I am trying to post a graph but it is not
  57. Mathematics- Algebra

    Two cars pass each other on a freeway at 6:30 a.m. The car driving north is traveling at an average speed of 60 mph and the car driving south is traveling at an average speed of 40 mph. At what time will they be 25 miles apart?
  58. physics

    when an object is 100m above the surface of earth. The earth's attraction for it is 10N. In order then the earth's attraction on the same object is only 5N. how far should be taken to object be away from surface of earth.
  59. chemestry please check my anwers.

    1.How do acid-base reactions differ from oxidation-reduction (or "redox") reactions? Answer Acid-base reactions involve an exchange of protons whereas redox reactions involve an exchange of electrons.<<< Acid-base reactions and redox reactions
  60. math physics

    A meteorite is a solid composed of stone and/or metal material from outer space that passes through the atmosphere and hits the earth’s surface. Find the kinetic energy of a meteorite with mass 250 kg that hits the earth at 25 km/s. Given: m=250kg
  61. math physics

    A meteorite is a solid composed of stone and/or metal material from outer space that passes through the atmosphere and hits the earth’s surface. Find the kinetic energy of a meteorite with mass 250 kg that hits the earth at 25 km/s. Given: m=250kg
  62. math physics

    A meteorite is a solid composed of stone and/or metal material from outer space that passes through the atmosphere and hits the earth’s surface. Find the kinetic energy of a meteorite with mass 250 kg that hits the earth at 25 km/s. Given: m=250kg
  63. Physics

    When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 75 kg man just before contact with the ground has a speed of 6.1 m/s. (a) In
  64. Physics 141

    A 45.0-kg skater is traveling due east at a speed of 2.85 m/s. A 72.5-kg skater is moving due south at a speed of 7.35 m/s. They collide and hold on to each other after the collision, managing to move off at an angle θ south of east, with a speed of
  65. English/Reading 10 HELP

    TO BUILD A FIRE Jack London Day had broken cold and gray, exceedingly cold and gray, when the man turned aside from the main Yukon trail and climbed the high earthbank, where a dim and little-traveled trail led eastward through the fat spruce timberland.
  66. PHYSICS

    A woman goes out running. She first travels 5.2km north. She then turns and travels 3.6km west. Finally, she turns again and travels 2.6km south. We are assuming a flat rectangular world. If a bird were to start out from the origin (where the woman starts)
  67. Physics

    A machine carries a 4.5 kg package from an initial position of di = (0.50 m) + (0.75 m) + (0.20 m) at t = 0 to a final position of df = (7.60 m) + (12.0 m) + (7.30 m) at t = 11 s. The constant force applied by the machine on the package is F = (2.00 N) +
  68. Physics

    A machine carries a 3.0 kg package from an initial position of di = (0.50 m) + (0.75 m) + (0.20 m) at t = 0 to a final position of df = (7.30 m) + (11.0 m) + (7.20 m) at t = 14 s. The constant force applied by the machine on the package is F = (2.00 N) +
  69. Physics to drwl please help

    Only need help with part c Mars orbits the Sun at a mean distance of 228 million km, in a period of 687 days. The Earth orbits at a mean distance of 149.6 million km in a period of 365.26 days. All answers should be in the range (0, 2pi) a) Suppose Earth
  70. physics

    find the rotational kinetic energy of the earth about the sun due to its orbital about the sun. The mass of the each M is 6 X 10^24 kg, the orbital radius r is 1.5 X 10^11 m and the rotational period T is 1 year. Hint, treat the earth as a point mass in
  71. trig

    A surveillance satellite circles the earth at a hight of h miles above the surface. Suppose that d is the distance, in miles, on the surface of the earth that can be observed from the satellite. find an equation that relates to central angel (theta) to the
  72. Physics

    The acceleration due to gravity on a planet other than the earth has a magnitude of 1.50 m/s2. As in examples 6, 7 and 8, a placekicker kicks a football with an initial speed of 20.3 m/s at an angle of 39.4 ° above horizontal. Assume that the ball is
  73. Algebra

    Using the formula: w=Cr^-2 where C is a constant, and r is the distance that the object is from the center of Earth. W is the weight. 1- Suppose an object is 100lbs when it is at sea level. Find the Value of C that makes the equation true. Sea level is
  74. Physics

    An electron is acted upon by a force of 7.00×10−15 N due to an electric field. Find the acceleration this force produces in each case: The electron's speed is 1.00 km/s . a=??m/s2 The electron's speed is 2.50×108 m/s and the force is parallel to the
  75. Science

    Waste produced by people in New York State has been dumped into the Atlantic Ocean, where it is distributed by surface ocean currents. Which coastal area is most likely to become polluted by this waste? A west coast of Mexico B south coast of South America
  76. Chemistry

    How is the ionic charge of a group 1A,2A, or 3A ion determined? Group IA elements have 1 electron in their outer shell. Group IIA elements have 2 electrons in their outer shell. Group IIIA elements have 3 electrons in their outer shell. These elements lose
  77. Physics

    The shuttle must perform the de-orbit burn to change its orbit so that the perigee, the point in the orbit closest to Earth, is inside of Earth's atmosphere. De-orbit maneuvers are done to lower the perigee of the orbit to 60 miles (or less). An altitude
  78. Physics

    The shuttle must perform the de-orbit burn to change its orbit so that the perigee, the point in the orbit closest to Earth, is inside of Earth's atmosphere. De-orbit maneuvers are done to lower the perigee of the orbit to 60 miles (or less). An altitude
  79. physics

    How can I find kinetic friction (Fk) without mu? I know the normal force which is 201N. The mass of the object is 30kg. This is the full questions of it helps. I just don't understand how to find kinetic friction 1. If a 30kg object experiences a normal
  80. science

    The true speed of a moving car on the Earth, if you want to be very precise, would be the speed of the car with respect to the ground Is this true? yeah it is true yeah it is true The true speed of a moving car on the Earth, if you want to be very precise,
  81. Chemistry

    How do I find the number of energy levels in a positive and a negative ion? And also how do I find the number of electrons in a ion and a atom?
  82. Trig

    A sail boat on lake Huron leaves Southampton and sails 20degrees west of north of 20km. At the same time, a fishing boat leaves Southampton and sails 30degrees west of south for 15 km. At this point, hot far apart are the boats, to the nearest metre? ( the
  83. physics

    If a person pushes on a block and it travels a distance of 6.0m before stopping. How far would the block travel if it were pushed with the same force, but on the moon(which has 1/6 of the earth's gravity).
  84. Physics

    If you throw a 36 kilogram rock off a cliff , how fast does it accelerate to the ground? The earth excerts a force of 200 Newtons on the rock.
  85. phys

    While spinning in a centrifuge, a 70.0 kg astronaut experiences an acceleration of 5.00 g, or five times the acceleration due to gravity on the earth. What is the centripetal force acting on her?
  86. AP physics

    The sun is below us at a magnitude of nearly a line with the earth center. Are we then Heavier at midnight due to the sun's gravitational force on us, than we are at noon? Explain
  87. geometry

    Satellite Explorer VII, with a = 4465 and b = 4462, and with the center of the Earth being at one of the foci of the ellipse. Assuming the Earth has a radius of about 3960 miles,graph both the orbits of Explorer VII and earths surface on the same axis if
  88. Science

    To lift an object weighing 21,000 N, how much force is needed on a piston with an area of 0.060 m2 if the platform being lifted has an area of 3.0 m2 ? If the weight is 21,000 N which is also a force and to find Buoyancy force then 3.0 m2 + .06 m2 = 3.6 m2
  89. Physics

    An electron is acted upon by a force of 3.50×10−15 N due to an electric field. Find the acceleration this force produces in each case: The electron's speed is 6.00 km/s . =3.84*10^15 The electron's speed is 2.60×108 m/s and the force is parallel to the
  90. Physics Please help!

    Calculate the position of the center of mass of the following pairs of objects. Use acoordinate system where the origin is at the center of the more massive object. Give youranswer not in meters but as a fraction of the radius as requested. Get data from
  91. physics

    A 2.00 kg block, on a horizontal surface with coefficient of static friction 0.900, is pushed by a force that is directed down at an angle of 30.0 degrees to the horizontal. Find the minimum magnitude of the force needed to get the block to start moving.
  92. physics

    a river flows due south with a speedof 2.0m/s.a man steers a motorboat across the river:his velocity relative to the river is 4.2m/s due east.the river is 800m wide.what is his velocity relative to the earth?
  93. physics

    A man of mass 78.5 kg walks down the aisle of an airplane at a speed of 1.40 m/s in the forward direction while the plane moves at a speed of 320 m/s relative to the earth. (a) Find the man's kinetic energy relative to the plane. (b) Find the man's kinetic
  94. NCSU

    A man of mass 83.5 kg walks down the aisle of an airplane at a speed of 1.60 m/s in the forward direction while the plane moves at a speed of 295 m/s relative to the earth. (a) Find the man's kinetic energy relative to the plane. (b) Find the man's kinetic
  95. Physics

    A man of mass 75.5 kg walks down the aisle of an airplane at a speed of 1.50 m/s in the forward direction while the plane moves at a speed of 305 m/s relative to the earth. (a) Find the man's kinetic energy relative to the plane. (b) Find the man's kinetic
  96. Math help

    The land on Earth’s surface is represented by the seven continents. Europe has 77% of the dry land while Africa has 20%. North America has 4/25 and Antarctica has 1/10 of the dry land. What fractional amount of the dry land is contained within the three
  97. Math

    The land on Earth’s surface is represented by the seven continents. Europe has 77% of the dry land while Africa has 20%. North America has 4/25 and Antarctica has 1/10 of the dry land. What fractional amount of the dry land is contained within the three
  98. physics

    how do i find the net force 30-N and a force 20 to show forces opposite and both in the same diection?
  99. physics

    A certain pendulum on Earth has a period of 1.6 s. What would be the period of this pendulum if it were taken to another planet that had 1.75 times the mass of the Earth and 2.5 times the Earth's radius? Express your answer in seconds to three significant
  100. biology 6

    the giant anteater of south america, the giant armadillo of north america, the giant pangolin of Africa and the spiny anteater of Oceania share many characteristics. They all eat ants, have long narrow snouts, few teeth and large salivary gland, yet they