1. Chemistry

    Why are the alkali and alkaline earth metals more reactive than other elements on the periodic table?
  2. Math

    A year on Mars is 686 Earth Days. (1) Which is longer, a year on Mars or a year on Earth? (2)By how many weeks is it longer? Submit two answers. Please explain how you got the answers. My 1st answer was Mars the 2nd answer I 82 1/2 weeks. Please help
  3. Physics

    A comet with a mass of 7.95 1011 kg strikes Earth at a speed of 22 km/s. (a) Find the kinetic energy of the comet in joules. ____ J (b) Compare the work that is done by Earth in stopping the comet to the 4.2 1015 J of energy that was released by the largest nuclear weapon ever...
  4. earth

    how would eath's gravity effect you in space??? At what altitude does the Earth's gravity no longer have an effect on the astronauts or the space shuttle???
  5. science

    The gravitational pull on Jupiter is 2.5 times greater than Earth's gravitational pull. If an object weighs 10 pounds on Earth, what will it weigh on Jupiter?
  6. Physics

    Mars has a radius of about 0.53 Earth radius and a mass of only 0.11 Earth mass. Estimate the acceleration due to gravity on Mars.
  7. physics

    Mars has a radius of about 0.38 Earth radius and a mass of only 0.11 Earth mass. Estimate the acceleration due to gravity on Mars.
  8. physics

    Mars has a radius of about 0.38 Earth radius and a mass of only 0.11 Earth mass. Estimate the acceleration due to gravity on Mars.'
  9. Help Physics

    Two equal-mass stars maintain a constant distance apart of 6.0 1010 m and rotate about a point midway between them at a rate of one revolution every 12.0 yr. (a) Why don't the two stars crash into one another due to the gravitational force between them? (b) What must be the ...
  10. math

    Oregon is about 400 miles from west to east, and 300 miles from north to south. If a map of Oregon is 15 inches tall (from north to south), about how wide is the map? PLEASE HELP AND EXPLAIN IT Set up a proportion: 15/300 (the ratio of inches to miles, north to south) and x/...
  11. geography

    Thank You and I did some more questions. Can you check them? 1. Is the Antarctic Circle north or south of the equator? South of the equator 2. All lines of longitude are measured east and west of what imaginary line? The Prime Meridian. Ms. Sue the 9th grade Algebra question I...
  12. physics

    A 4.92E+2 kg hot-air balloon takes off from rest at the surface of the earth. The nonconservative wind and lift forces take the balloon up, doing +9.81E+4 J of work on the balloon in the process. At what height above the surface of the earth does the balloon have a speed of 7....
  13. Precalculus

    A nautical mile equals the length of arc subtended by a central angle of 1 minute on a great circle on the surface of Earth. If the radius of Earth is taken as 3960 miles, express 1 nautical mile in terms of ordinary, or statute, miles.
  14. college physics

    Although astronauts appear weightless, they are not. They only appear weightless because they are in free fall. If a 79 kg astronaut is orbiting Earth with an orbital radius of 5.31×107 m, determine how much the astronaut would weigh. Earth's mass is 5.974 1024 kg.
  15. Physics

    A skydiver is jumping from an airplane traveling at 10.0 m/s. The plane is 3520 m above the earth. The sky diver pulls his cord at 1760 m above the earth. Neglecting air resistance, how far does the skydiver travel horizontally before pulling the cord?
  16. Science

    The rock cycle suggests that A)rocks are always added to Earth's mass. B)rocks are continuously being recycled into different forms. C)rocks disappear from Earth as they go underground. D)rocks always stay in the same form. My answer is A... is that right??
  17. math

    A floor consists of parallel planks which have a two foot width. A circular disc of diameter one foot is randomly and uniformly dropped onto the planks. Determine the probability that the disc does not touch the line between two planks. Determine also the expected distance ...
  18. English-Accented Syllables

    I don't understand how to determine how many accented syllables there are in lines of poetry... How do you tell? Example: When the north wind blows its icy air to cool the earth,
  19. Science

    Give two advantages that a telescope lens or mirror of large diameter has over one of small diameter
  20. Math

    One tire has a diameter of 7 in and another has a diameter of 12 in. What is the difference in the distance the tires make in two revolutions? I don't get the question could you explain?
  21. Science 10

    I am doing my science 10 by correspondence and I came upon a question that puzzles me. Why are modern light microscopes called Compound microscopes. That and How would I "determine theactual size of the cells shown in the illistration if the field diameter measures 2.2 mm"??? ...
  22. physics

    Ricardo and Jane are standing under a tree in the middle of a pasture. An argument ensues, and they walk away in different directions. Ricardo walks 25.0 in a direction 60.0 west of north. Jane walks 14.0 in a direction 30.0 south of west. They then stop and turn to face each ...
  23. Physics

    A small metal bead, labeled A, has a charge of 26 nC . It is touched to metal bead B, initially neutral, so that the two beads share the 26 nC charge, but not necessarily equally. When the two beads are then placed 5.0 cm apart, the force between them is 4.5×10−4 N . Assume...
  24. Physics

    I have tried this question over and over and not sure if the answer is 16 west or 190 south west please help. Airplane One flies due east at 250 km/h relative to the ground. At the same time, Airplane Two flies 325 km/h, 35° north of east relative to the ground. What is the ...
  25. Earth Science

    i need to find out how many rabbits it would take to eat 24.447,000 dandelions in 30 minutes at a rate of one dandelion in 7 seconds... any ideas how to set this up?
  26. trig

    the 40ft. pole is braced by , a wire from its top in a point 60ft. from its base up, snd 18° slope. how long is the wire?
  27. mathematics

    In a mathematical equation, the coefficient is A. the numeric value of the unknown that makes an equation true. B. the term brought from one side of an equation to the other by performing the opposite operation. C. a number or quantity placed before another quantity to ...
  28. Math HELP PLEASE

    find an expression for the magnitude of the initial velocity that a projectile must possess in order to leave the earth when air friction is negelcted. The gravitational constant is given as G= 6.67428*10^-11 m^3 kg^-1 s^-2 Please give lots of details in answer
  29. physics

    Two point charges are separated by 6.4 cm. The attractive force between them is 10 N. Suppose that the charges attracting each other have equal magnitude. Rearrange Coulomb's law and find the magnitude of each charge
  30. Astronomy

    The volume of a ball is given in terms of its radius by V=4π3R3. Use this to find the average density of Saturn, i.e. the mass per unit volume. Use Earth’s mass in kg from the Table of Constants to express your answer in kgm3. Note for comparison that water has a ...
  31. physics

    Two Small sphere are given positive electrical change. When they are 40cm apart the repulsion force between them has magnitude 0.25N what the charge on each sphere if two changes are equal
  32. math

    there are two 1's,two 2's,and two 3's.There is one digit between the two 1's, there are two digits between the two 2's, and there are three digits between the two 3's. Holding number cards,can you duplicate this sequence of numbers?
  33. science

    how is the air we breath today different from 3.6 billion years ago? http://en.wikipedia.org/wiki/Earth's_atmosphere#Evolution_of_the_Earth.27s_atmosphere http://eesc.columbia.edu/courses/ees/climate/lectures/earth.html
  34. Calc

    A spherical snowball is placed in the sun. The snowball melts so that it's surface area decreases at a rate of 2 cm2 /min. Find the rate at which the diameter decreases when the diameter is 8 cm.
  35. calculus

    A spherical snowball is placed in the sun. The snowball melts so that it's surface area decreases at a rate of 2 cm2 /min. Find the rate at which the diameter decreases when the diameter is 8 cm
  36. SCIENCE

    Car headlight circuit - is this possible or do I need two separate circuit diagrams? I have the following components: 12 Volt Battery, 1 x Double filament lamp, two switches (assume stay closed when switched). Draw a circuit diagram using these components which would allow: a...
  37. Physics

    Two boxes of mass 7.40 and 7.00 kg are in contact and are accelerated across a horizontal surface by an force of 51.49 N applied parallel to the surface and pushing on the lighter box. The magnitude of the frictional force between the surface and the lighter mass is 9.26 N and...
  38. PHYSICS

    Two crates , one with mass 4.00 kg and the other with 6.00 kg, sit on the frictionless surface of a frozen pond, connected by a light rope. Awoman wearing golf shoes(so she can get traction on the ice)pulls horizontally on the 6.00-kg crate with a force F that gives the crate ...
  39. physics

    pls explain to me how you add 65km{North 85 degreesWest], 3500m[South 10 West}, 6000m{East 70 degrees South], 54km[North 60 degrees East]. pls explain to me how i should add these vectors. I really need help. pls help
  40. earth science

    The Mororovicic Discontinuity marks the change in rock density and elasticity between the:
  41. 5th grade science

    What is the continous movement of water between Earth's surface and the air?
  42. Earth Science

    Is there a direct relationship between the eccentricity of its orbit and the distance a planet is from the sun?
  43. miami dade

    a student designed an experiment to demonstrate the interactions between earth systems
  44. Chemistry

    Hi, This is one of my chem hw problems. Does anyone have links to websites that might help me solve this..or equations? It sounds like there are two parts to the question but I'm not sure. Volts and Joules? 1. Electrons are used to determine the structure of crystal surfaces. ...
  45. physics

    work is being done when a force: a) is exerted while pulling a wagon up a hill b) acts vertically on a cart that can only move horizontally c) is exerted by one team in a tug-of-war when there is no movement d) of gravitational attraction acts on a person standing on the ...
  46. Global Studies

    Although the Amazon Basin receives more than 80 inches of rain per year, South America also has the driest place on Earth, know as a. Death valley b. Gobi desert c. Atacama desert*** d. the Caribbean
  47. Chemistry

    What properties differ between the elements in the akali metals and the elements in the akaline earth metals? The akali metals have a charge of 1+, and the akaline earth metals have a charge of 2+.
  48. Science

    Two south poles or two north poles are called...
  49. PHYSICS

    (#1) If two pith balls - one which is neutral and another which has a charge of -9.6 uC (micro-Coulombs) - are touched together, how many extra electrons will each ball have? (#2) Charge q1 = 6 uC is at the origin, charge q2 = 7 uC is at y = 2m, x = 0, charge q3 = 1.5 uC is at...
  50. Math Please Help

    Simon travels north and south from Main Station. The distance, in km, of the train from Main Station is modeled by the function 𝑑(𝑡) = 𝑡 3 − 9𝑡 2 + 6𝑡, where North is positive and South is negative. Time elapsed after the start of ...
  51. Physics

    How much force are you exerting on the earth right now? How can a rocket operate in outer space? Describe the process of walking.
  52. physics

    two equal masses of 5kg are placed on two vertex of an an equilateral triangle and 20 kg mass on the third.each side is 20 cm long. find the force acting on 1 kg mass kept at the centroid of the triangle.
  53. algerbra

    sasha researched the size of zoos in her state. she found that the zoo in the north part of the state is almost twice as large as the zoo in the south. she also found that the zoo in the south part of the state has 200 fewer than twice the number of animals as the northern zoo...
  54. Physics

    Suppose that a binary star system consists of two stars of equal mass. They are observed to be separated by 380 million kilometers and take 9.0 Earth years to orbit about a point midway between them. What is the mass of each? ------------------------------- I've worked this ...
  55. Geometry

    A satellite in a nearly circular orbit is 2000 km above Earth's surface. The radius of Earth is approximately 6400 km. If the satellite completes its orbit in 112 hours, calculate the speed of the satellite in kilometers per hour. Please help me. I have a math test tomorrow.
  56. Math

    Monica stepped outside and began to think how fast she is moving even when she is standing still. Assume that the earth is a sphere with a radius of 3960 miles and Monica is at a latitude of 13∘N. What is Monica's speed due solely to the rotation of the earth in miles ...
  57. Mathematics

    Monica stepped outside and began to think how fast she is moving even when she is standing still. Assume that the earth is a sphere with a radius of 3960 miles and Monica is at a latitude of 13∘N. What is Monica's speed due solely to the rotation of the earth in miles ...
  58. Math

    Monica stepped outside and began to think how fast she is moving even when she is standing still. Assume that the earth is a sphere with a radius of 3960 miles and Monica is at a latitude of 13∘N. What is Monica's speed due solely to the rotation of the earth in miles ...
  59. MATH HELP

    Monica stepped outside and began to think how fast she is moving even when she is standing still. Assume that the earth is a sphere with a radius of 3960 miles and Monica is at a latitude of 13∘N. What is Monica's speed due solely to the rotation of the earth in miles ...
  60. Please Please Help-Physics

    I am having trouble figuring out this question: Part 1: A long staight wire carries a current due East. This wire creates, at point #1, a magnetic field that is derected at 40 deg below due South. From point #1, the wire is located: 50 deg below due North 50 deg below due ...
  61. PHYSICS!!

    A 10.2 kg crate is pulled up a rough incline with an initial speed of 1.5 m/s. The pulling force is 123.0 N parallel to the incline, which makes an angle of 14.6◦ with the horizontal. The coecient of kinetic friction is 0.39 and the crate is pulled a distance of 8.1 m. ...
  62. Calculus

    Can anyone help me with these two optimization problems? A boat leaves a dock at 9:00 P.M. and travels due south at a speed of 20 km/h. Another boat has been heading due east at 15 km/h and reaches the same dock at 10:00 P.M. How many minutes after 9:00 P.M. were the two boats...
  63. Science , Biology

    Cretaceous extinction... The evidence tells you that “overwhelming evidence suggests that the extinction was caused by a 10-km-diameter asteroid that struck Earth.” Suggest at least three lines of evidence that might have led scientists to this conclusion. Could you please...
  64. science

    If Earth is 149.6 million Kilometers from the sun, or 93 million miles away. suppose there was an imaginary road from earth to the sun. If you were in a car traveling 100 km an hour, it would take you 1,490,000 hours or just 170 years to reach the sun. If it took 170 years to ...
  65. physics

    Two cars are driving toward each other on a straight, flat Kansas road. The Jeep Wrangler is traveling at 84 km/h north and the Ford Taurus is traveling at 43 km/h south, both measured relative to the road. What is the velocity of the Jeep relative to an observer in the Ford?
  66. physics

    Two cars are driving toward each other on a straight, flat Kansas road. The Jeep Wrangler is traveling at 84 km/h north and the Ford Taurus is traveling at 43 km/h south, both measured relative to the road. What is the velocity of the Jeep relative to an observer in the Ford?
  67. Exploring Space

    if a satellite were to be launched with too little speed or too much speed then what would happen? If a sattellite were to be launched with too much speed then the friction in the air would make it heat up to the point where it would burn up. Earth's gravity wouldn't be strong...
  68. PHYSICS

    Two cars collide at an intersection. Car A, with a mass of 2000kg, is going from west to east, while car B, of mass 1300kg, is going from north to south at 15.0m/s. As a result of this collision, the two cars become enmeshed and move as one afterwards. In your role as an ...
  69. Physics

    In 1996, NASA performed an experiment called the Tethered Satellite experiment. In this experiment a 2.20 104-m length of wire was let out by the space shuttle Atlantis to generate a motional emf. The shuttle had an orbital speed of 7.50 103 m/s, and the magnitude of the earth...
  70. Physics

    In 1996, NASA performed an experiment called the Tethered Satellite experiment. In this experiment a 2.20 104-m length of wire was let out by the space shuttle Atlantis to generate a motional emf. The shuttle had an orbital speed of 7.50 103 m/s, and the magnitude of the earth...
  71. 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 horizontal. Assume that ...
  72. College Physics

    Sirius is about 9.0 light-years from Earth. To reach the star by spaceship in 10 years (ship time), how fast must you travel? How long would the trip take according to an Earth-based observer? How far is the trip according to you?
  73. colleg physics

    Sirius is about 9.0 light-years from Earth. To reach the star by spaceship in 10 years (ship time), how fast must you travel? How long would the trip take according to an Earth-based observer? How far is the trip according to you?
  74. college physics

    Sirius is about 9.0 light-years from Earth. To reach the star by spaceship in 10 years (ship time), how fast must you travel? How long would the trip take according to an Earth-based observer? How far is the trip according to you?
  75. Physics

    If a projectile is launched from Earth with a speed equal to the escape speed, how high above the Earth's surface is it when its speed is three-fifths the escape speed? I keep getting the answer 2.56x10^6 m after solving it a few different ways. Help would be great.
  76. PHYSICS

    Light is shining perpendicularly on the surface of the earth with an intensity of 680 W/m2. Assuming that all the photons in the light have the same wavelength (in vacuum) of 478 nm, determine the number of photons per second per square meter that reach the earth.
  77. physics

    Light is shining perpendicularly on the surface of the earth with an intensity of 680 W/m2. Assuming that all the photons in the light have the same wavelength (in vacuum) of 478 nm, determine the number of photons per second per square meter that reach the earth.
  78. physics

    Light is shining perpendicularly on the surface of the earth with an intensity of 680 W/m2. Assuming that all the photons in the light have the same wavelength (in vacuum) of 521 nm, determine the number of photons per second per square meter that reach the earth.
  79. Physics (Online w/ no teacher)

    Find the change in the force of gravity between two planets when the distance between them is decreased by a factor of 5.
  80. physics

    A charge of 1.5uC is placed at the origin, and a charge of 3uC is placed at x = 1.5m. Locate the point between the two charges where the electric field is zero? Q1 P Q2 x------------*-----------. 0 <---------1.5m----------->
  81. Physics

    Hello everyone I know that when a force is applied it has to exert a force opossite But this really is not in my head can someone please give me an evidence or even a diagram showing how can we exert an opposite force if we are walking forwards Thanks alot When we are walking ...
  82. Math

    Six friends want to buy pizza and need to decide between two deals. The first deal is for two pizzas for $7.00 each for a pizza with a 10 inch diameter. Or a second deal with one pizza with a 14 inch diameter for $15.00. The friends decide to buy the offer with the most pizza ...
  83. math2

    I was solving a problem. In It r have been given that two lines are perpendicular to each other The equation of one line 2x-3y+4=0 Now i have to find the equation of another line We can find it by finding the slope of the abovementioned line( the other line) But we are ...
  84. Physics

    A 23.7 kg child, with a 4.35 kg backpack on his back, first stands on a sidewalk and then jumps up into the air. Find the net force (positive up/negative down) on Earth due to the child when the child is (c) standing still and (d) in the air.
  85. physics

    An object moves along a circular path with a constant speed, |⃗vo|. (Semi Circle with point A on one side point B on the other. Looks like a 90 degree angle with points A and B on either side of the hypotenuse.) The average acceleration in going from A to B is 1. zero 2...
  86. Earth Science (check answers)

    Describe the importance of maintaining the ocean ecosystem. It is important to maintain because the ocean ecosystems because it provides reefs that support a complex ecosystem of ocean organisms that live and help each other to survive. Virtually every phyla on Earth is ...
  87. Physics

    A 0.7 um-diameter droplet of oil, having a charge of +e, is suspended in midair between two horizontal plates of a parallel-plate capacitor. The upward electric force on the droplet is exactly balanced by the downward force of gravity. The oil has a density of 860 (kg/m^3), ...
  88. Physics

    If in a manufacturing company they want to produce a system where the force F1 must be 10% of the output force F2.if the area of the pistol (where F1 is applied)is 450 spuare milimetre.calculate the diameter of the pistol two where F2 is an output force
  89. math

    Can someone please take a look at these results and make sure they're correct? Thank you! 5. The Leaning Tower of Pisa leans toward the south at an angle of 5.5 degrees. One day near noon its shadow was measured to be 84.02m long and the angle of elevation from the tip of the ...
  90. English 2

    2. The overall message of "To Every Thing There Is A Season" is a. every human emotion and activity has an appropriate time in life b. life is a meaningless cycle of pleasure and pain c. humans have been given power over nature, and they should use it wisely d. there is no ...
  91. Science

    In what way is erosion NOT like weathering? A)It is a force that changes the earth's surface B)It is a destructive force C)It changes rocks in some way D)It breaks down rocks I think D??
  92. reading

    Examine the evidence of the Earth's shape. The sharp horizon at first suggests a flat Earth with an edge. But as you walk toward the horizon, the "edge" recedes ahead of you, implying that the Earth's surface is curved. Look also at a ship sailing out to sea. It does not stay ...
  93. maths

    from a certain spot, the top of a triangle had an angle of elevation of 40 degree. move 15meter in a straight line towards the flag pole.Now to the top has an angle of elevation of 60degree.Find the height of the flagpole and it's distance from the second point.
  94. physics

    A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
  95. Physics help

    A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
  96. physics

    A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
  97. physics

    A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
  98. physics

    A satellite is orbit about earth, its orbital radius is 3.43*10e7m.The mass of the satellite is 9166kg and the mass of earth is 5.974*10e24kg. Determine the orbital speed of the satellite in mi/s. 1mi/s=1609m/s.
  99. earth

    how long does it take for light from Jupiter to come to earth. for example tonight the planet Jupiter can be seen by the moon, 2/25/12 and we see the light from the planet and how old is that light. thanks. jerry in colorado USA
  100. physics

    Mars Rover When the Mars rover was deployed on the surface of Mars in July 1997, radio signals took about 12 min to travel from Earth to the rover.How far was Mars from Earth at that time?
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