Elisa

Most popular questions and responses by Elisa
  1. Physics

    One of the fastest recorded pitches in major-league baseball, thrown by Billy Wagner in 2003, was clocked at 101.0 mi/h . If a pitch were thrown horizontally with this velocity, how far would the ball fall vertically by the time it reached home plate, 60.5

    asked on June 1, 2008
  2. physics

    A jet airliner moving initially at 300 mi/h due east enters a region where the wind is blowing at 100 mi/h in a direction 26.0° north of east. What is the new velocity of the aircraft relative to the ground? in m/h at degrees North of east.

    asked on June 2, 2008
  3. Physics

    Two blocks are fastened to the ceiling of an elevator as in Figure P4.19. The elevator accelerates upward at 2.00 m/s2. The blocks both have a mass of 14.0 kg. Find the tension in each rope. top rope: bottom rope:

    asked on June 9, 2008
  4. Chemistry

    Acid spills are often neutralized with sodium carbonate. For example Na2CO3 (s) + H2SO4 (aq)  Na2SO4 (aq) + CO2 (g) + H2O (l) An instructor dropped a 2.50 L bottle of 18.0 M H2SO4 on a cement floor. How much sodium carbonate would be required to

    asked on March 18, 2012
  5. physics

    A 45.0 kg girl is standing on a 163 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.45 m/s relative to the plank. (a)

    asked on July 7, 2008
  6. physics

    An object with mass m1 = 5.00 kg, rests on a frictionless horizontal table and is connected to a cable that passes over a pulley and is then fastened to a hanging object with mass m2 = 9.0 kg, as shown in Figure P4.30. Find the acceleration of each object

    asked on June 9, 2008
  7. physics

    A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run

    asked on June 2, 2008
  8. physics

    The force shown in the force-time diagram in Figure P6.11 acts on a 1.4 kg object. (a) Find the impulse of the force. (b) Find the final velocity of the mass if it is initially at rest. (c) Find the final velocity of the mass if it is initially moving

    asked on July 7, 2008
  9. physics

    In a popular amusement park ride, a rotating cylinder of radius 4.00 m is set in rotation at an angular speed of 5.00 rad/s. The floor then drops away, leaving the riders suspended against the wall in a vertical position. What minimum coefficient of

    asked on July 11, 2008
  10. physics

    A 175 kg merry-go-round in the shape of a uniform, solid, horizontal disk of radius 1.50 m is set in motion by wrapping a rope about the rim of the disk and pulling on the rope. What constant force would have to be exerted on the rope to bring the

    asked on July 20, 2008
  11. physics

    Calculate the magnitude of the linear momentum for the following cases. (a) a proton with mass 1.67 10-27 kg, moving with a speed of 4.00 106 m/s (b) a 16.5 g bullet moving with a speed of 270 m/s (c) a 70.5 kg sprinter running with a speed of 12.5 m/s (d)

    asked on July 7, 2008
  12. physics

    1. A centrifuge in a medical laboratory rotates at an angular speed of 3650 rev/min. When switched off, it rotates through 50.0 revolutions before coming to rest. Find the constant angular acceleration of the centrifuge. 2. A ball of mass 0.120 kg is

    asked on July 6, 2008
  13. chemistry

    what volume of oxygen gas is needed to completely combst 0.202L of butane (c4h10)gas?

    asked on May 20, 2011
  14. physics

    A bat flying at 6.00 m/s emits a chirp at 40.0 kHz. If this sound pulse is reflected by an insect moving away from the bat at 2.00 m/s, what is the frequency of the echo received by the bat? Assume the air temperature is 25.0 ˚C. Would I need two

    asked on August 6, 2008
  15. physics

    The force shown in the figure below is the net eastward force acting on a ball. The force starts rising at t=0.012 s, falls back to zero at t=0.062 s, and reaches a maximum force of 35 N at the peak. Determine with an error no bigger than 25% (high or low)

    asked on July 2, 2008
  16. Physics

    Find the tension in the two wires that support the 100 N light fixture. Assume θ is 39°. left wire: right wire:

    asked on June 9, 2008
  17. Math

    The ratio of golf balls to tennis balls in the coach's bag is 20 to 5. If there are 100 golf balls in the bag, how many tennis balls are in the bag?

    asked on May 16, 2016
  18. Physics

    A simple pendulum is 9.00 m long. (a) What is the period of simple harmonic motion for this pendulum if it is hanging in an elevator accelerating upward at 2.00 m/s2? I keep getting 6.7, but it's wrong

    asked on August 4, 2008
  19. physics

    A ball thrown straight upward returns to its original level in 2.50s. A second ball is thrown at an angle of 36.degrees above the horizontal. What is the initial speed of the second ball if it also returns to its original level in 2.50

    asked on September 17, 2011
  20. physics

    A ball of mass 0.120 kg is dropped from rest from a height of 1.25 m. It rebounds from the floor to reach a height of 0.600 m. What impulse was given to the ball by the floor?

    asked on July 7, 2008
  21. Chemistry

    Is this reaction exothermic or endothermic? Fe(NO3)3+ NaSCN

    asked on December 11, 2012
  22. physics

    The force sensor measures the force on the sensor due to the bumper, but the cart's momentum change arises from the force on the cart due to the bumper. Which of the following facts are needed to assert that the magnitude of these two forces are nearly

    asked on July 2, 2008
  23. physics

    A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run

    asked on June 2, 2008
  24. physics

    A 705 N man stands in the middle of a frozen pond of radius 4.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 1.2 kg physics textbook horizontally toward the

    asked on July 6, 2008
  25. physics

    A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 20.0° below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a

    asked on June 1, 2008
  26. Physics

    A 4.0 g bullet leaves the muzzle of a rifle with a speed of 310 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.9 m long barrel of the rifle?

    asked on June 9, 2008
  27. physics

    Objects of masses m1 = 4.00 kg and m2 = 9.00 kg are connected by a light string that passes over a frictionless pulley as in Figure P4.48. The object m1 is held at rest on the floor, and m2 rests on a fixed incline of θ = 42.0°. The objects are released

    asked on June 8, 2008
  28. physics

    A rotating wheel requires 5.00 s to rotate 30.0 revolutions. Its angular velocity at the end of the 5.00 s interval is 100.0 rad/s. What is the constant angular acceleration of the wheel?

    asked on July 6, 2008
  29. Math

    Brent counted 10 red cards, 10 black cards, and 20 blue cards in a deck of cards. What is the ratio of red cards to the other cards?

    asked on May 14, 2016
  30. MATH HW HELP!!

    stuart daniels estimates that he will need 25,000 to set up a small business in 7 years. how much must Stuart invest now at 12%interest compounded quarterly to achieve his goal?

    asked on May 20, 2014
  31. Algebra

    A dress normally selling for $60 was on sale for $48. What was the percent discount?

    asked on August 10, 2013
  32. physics

    calculate your average walking speed when you step 1.0 m in 0.5 s

    asked on September 18, 2017
  33. physics

    1. A 10.0 g object moving to the right at 25.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the opposite direction at 36.0 cm/s. Find the velocity of each object after the collision. 10.0 g object: 15.0g object: 2. A dentist's

    asked on July 7, 2008
  34. Physics

    Two packing crates of masses m1 = 10.0 kg and m2 = 3.50 kg are connected by a light string that passes over a frictionless pulley as in Figure P4.26. The 3.50 kg crate lies on a smooth incline of angle 37.0°. Find the acceleration of the 3.50 kg crate. up

    asked on June 9, 2008
  35. Physics

    Can't get correct answer An object weighing 340 N in air is immersed in water after being tied to a string connected to a balance. The scale now reads 260 N. Immersed in oil, the object weighs 290 N. (a) Find the density of the object. kg/m3 (b) Find the

    asked on July 22, 2008
  36. Math

    Nelly spends 25% of her free time surfing the Internet. If she spends approximately 1 hour per day surfing the Internet, how many hours of free time does she have each day?

    asked on May 14, 2016
  37. physics

    A 3.6 kg mass hangs at one end of a rope that is attached to a support on a railroad car. When the car accelerates to the right, the rope makes an angle of 1.0° with the vertical. Find the acceleration of the car.

    asked on June 9, 2008
  38. math

    Twenty-five is equal to one more than eight times a number. What is the number?

    asked on December 7, 2016
  39. physics

    A simple pendulum with a length of 1.50 m is suspended from the ceiling of a train. What is the period of simple harmonic motion for the pendulum if the train is moving up an incline of 15.0˚ with an acceleration of 3.00 m/s²? Don't know how to do,

    asked on August 6, 2008
  40. physics

    Determine the elongation of the rod in if it is under a tension of 5.7E10^3 N. The rod is made of aluminum and copper. From the aluminum to the copper section it measures 1.3m and from the copper section to the end it measures 2.6m with a radius of 0.2cm.

    asked on July 21, 2008
  41. physics

    A bat flying at 5.0 m/s emits a chirp at 35 kHz. If this sound pulse is reflected by a wall, what is the frequency of the echo received by the bat? I keep getting the wrong answer, don't understand.

    asked on August 4, 2008
  42. Physics

    A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 15.0 m/s. The cliff is h = 66.0 m above a flat horizontal beach. How long after being released does the stone strike the beach below the cliff? I got 3.67

    asked on June 1, 2008
  43. physics

    A woman at an airport is towing her 27.0 kg suitcase at constant speed by pulling on the strap at an angle θ above the horizontal. She pulls on the strap with a 32.0 N force, and the friction force on the suitcase is 11.0 N. (a) What angle does the strap

    asked on June 8, 2008
  44. physics

    An airplane flies 200 km due west from city A to city B and then 280 km in the direction of 30.5° north of west from city B to city C. (a) In straight-line distance, how far is city C from city A? (b) Relative to city A, in what direction is city C? The

    asked on June 2, 2008
  45. Physics

    A boat moves through the water of a river at 5 m/s relative to the water, regardless of the boat's direction. If the water in the river is flowing at 1.3 m/s, how long does it take the boat to make a round trip consisting of a 215 m displacement downstream

    asked on June 1, 2008
  46. physics

    An archer shoots an arrow toward a 300 g target that is sliding in her direction at a speed of 2.35 m/s on a smooth, slippery surface. The 22.5 g arrow is shot with a speed of 41.0 m/s and passes through the target, which is stopped by the impact. What is

    asked on July 7, 2008
  47. Pre Algebra

    The first side of a triangle is 8 meters longer than twice the second side. The third side is 3 times the second side. The perimeter is 128 meters. Find the lengths of the three sides.

    asked on January 13, 2010
  48. Physics

    The force exerted by the wind on the sails of a sailboat is 310 N north. The water exerts a force of 240 N east. If the boat (including its crew) has a mass of 330 kg, what are the magnitude and direction of its acceleration? magnitude in m/s2 direction in

    asked on June 9, 2008
  49. applications involving quadratic

    Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5km/h. Find Abby’s speed in still water.

    asked on June 19, 2011
  50. algebra 1

    Write the equation for the line that passes through the point (6,7) and has a slope of 1/2. Give as a simplified fraction. Again, I have y equals 1/2x but not sure for the rest.

    asked on September 26, 2009
  51. physics

    1. A 3.25 kg steel ball strikes a wall with a speed of 10.0 m/s at an angle of 60.0° with the surface. It bounces off with the same speed and angle. If the ball is in contact with the wall for 0.195 s, what is the average force exerted on the ball by the

    asked on July 6, 2008
  52. physics

    A stone is thrown downward into a well with an initial speed of 5.00 m/s. The sound of splash is heard 1.50 s later. Find the depth of the well if the air temperature is 15.0 ˚C?

    asked on August 6, 2008
  53. Physics

    A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run

    asked on June 1, 2008
  54. Calculus

    Suppose that the number of bacteria in a culture at time t is given by N = 4950 ( 28 + t*e ^(-t/24)) Find the LARGEST and SMALLEST number of bacteria in the culture during the time interval 0 ≤ t ≤ 140

    asked on November 29, 2010
  55. Algebra 1

    Write the equation in standard form for the line that passes through (6, -1) and (10,-*) So far I have -8-1 is -9 and 10-6 is 4, is the -9 correct? Then y plus 10 equals 9/4(x - 8) Then multiply by 2 so 2y plus 20 equals 18/4x - 146/4 Is this correct so

    asked on September 29, 2009
  56. physics

    A uniform string fixed at one end passes over a pulley and then is attached to a hanging object. The string is horizontal between the fixed end and the pulley. When you let the hanging object oscillate in the vertical plane, the fundamental frequency of

    asked on August 6, 2008
  57. Physics

    Please help. I got 338.82 for the velocity and wanted to get the distance, but I can't seem to do it because I don't have the wavelength. Please help! A stone is dropped from rest into a well. The sound of the splash is heard exactly 2.20 s later. Find the

    asked on August 4, 2008
  58. physics

    A bat hits a moving baseball. If the bat delivers a net eastward impulse of 0.7 N-s and the ball starts with an initial horizontal velocity of 3.8 m/s to the west and leaves with a 5.2 m/s velocity to the east, what is the mass of the ball (in grams)?

    asked on July 2, 2008
  59. Physics

    A boat moves through the water of a river at 5 m/s relative to the water, regardless of the boat's direction. If the water in the river is flowing at 1.3 m/s, how long does it take the boat to make a round trip consisting of a 215 m displacement downstream

    asked on June 1, 2008
  60. physics

    An 8.00 g bullet is fired into a 180 g block that is initially at rest at the edge of a table of 1.00 m height. The bullet remains in the block, and after the impact the block lands d = 2.2 m from the bottom of the table. Determine the initial speed of the

    asked on July 6, 2008
  61. math

    A 5% alcohol solution is mixed with 15% alcohol solution to make a 25mlof a 9% solution. How much of each alcohol solution is used?

    asked on October 29, 2007
  62. Algebra

    A box contains 4 quaters, 3 dimes, and 2 nickels. you draw out two coins and keep them both. What is the probability that both are quaters?

    asked on August 8, 2013
  63. Calculus

    Suppose that the number of bacteria in a culture at time t is given by N = 4950 ( 28 + t*e ^(-t/24)) Find the LARGEST and SMALLEST number of bacteria in the culture during the time interval 0 ≤ t ≤ 140

    asked on November 29, 2010
  64. Algebra 1

    Graph y-7 equals 9(x plus 6) So 9x plus 54 54 plus 7 is 61 So y equals 9x plus 61. is it correct?

    asked on September 29, 2009
  65. math

    in a school of 100 students, 59 are taking math, 51 are in english, 35 are in history, 24 are in both math and english, 19 are in both english and history, 13 in both math and history, and 11 in all three courses. how many students are taking: a) none of

    asked on October 18, 2008
  66. Physics

    The four tires of an automobile are inflated to a gauge pressure of 1.8E10^5 Pa. Each tire has an area of 0.025 m2 in contact with the ground. Determine the weight of the automobile. I was helped with this before, but the answer was wrong. Can someone

    asked on July 21, 2008
  67. physics

    The four tires of an automobile are inflated to a gauge pressure of 1.8 multiplied by 105 Pa. Each tire has an area of 0.025 m2 in contact with the ground. Determine the weight of the automobile. No idea how to start, please help.

    asked on July 20, 2008
  68. physics

    An airplane flies 200 km due west from city A to city B and then 280 km in the direction of 30.5° north of west from city B to city C. (a) In straight-line distance, how far is city C from city A? in km? (b) Relative to city A, in what direction is city

    asked on June 1, 2008
  69. Intermidiate Algebra

    Andrew factored the expression -12x^3-28x^2-3x as -4x (3x^2-7x+9). But when Melissa applied the distributive law and multiplied out -4x (3x^2-7x+9), she got -12x^3+28x^2-36x; thus, Andrew’s solution does not appear to check. Why is that? Please help

    asked on June 19, 2011
  70. math

    A particle moves along the s-axis. Use the given information to find the position of the particle. v(t)=8t3 ; s(0) = 5.

    asked on December 19, 2010
  71. Calc - Please help

    A particle moves along the s-axis. Use the given information to find the position of the particle. v(t) = 8t3; s(0) = 5.

    asked on December 19, 2010
  72. physics

    An archer shoots an arrow toward a 300 g target that is sliding in her direction at a speed of 2.35 m/s on a smooth, slippery surface. The 22.5 g arrow is shot with a speed of 41.0 m/s and passes through the target, which is stopped by the impact. What is

    asked on July 6, 2008
  73. physics

    1. It has been suggested that rotating cylinders about 11 mi long and 5.2 mi in diameter be placed in space and used as colonies. What angular speed must such a cylinder have so that the centripetal acceleration at its surface equals the free-fall

    asked on July 14, 2008
  74. Algebra

    Megan factored the expression 72x^2-43x+6 as (9x-3)(8x-2). But when Jacob applied the FOIL principle and multiplied out (9x-3)(8x-2), he got72x^2-42x+6; thus, Megan’s solution does not appear to check. Why is that? Please help Megan to understand this

    asked on June 20, 2011
  75. algebra

    Factor out the greatest common factor from the expression 36x^3-30x^2

    asked on June 19, 2011
  76. Intermedia Algebra

    Solve by factoring: 2a^2 − 3a = −5

    asked on June 19, 2011
  77. Calculus

    Suppose that the number of bacteria in a culture at time t is given by N = 4950 ( 28 + t*e ^(-t/24)) Find the LARGEST and SMALLEST number of bacteria in the culture during the time interval 0 ≤ t ≤ 140 .

    asked on November 29, 2010
  78. Algebra 1

    Could you please show me how to do this. Write an equation of the vertical and horizontal lines that pass through the given point (6,-6) y equals? x equals ?

    asked on September 29, 2009
  79. fraction help algebra

    Write the equation passing through the points (-9, 6 ) and (1, -5). The worksheet has multiple choice, so I know y intercept is either 39/10 or -39/10. I have -11/10x plus b then -11 (1) is -11 10(1) is 10 Then -5 plus 11/10 I change -5 to -15/10 but I'm

    asked on September 26, 2009
  80. algebra again

    Write an equation that passes through the points (4, 3) and (2, -2) I have -2 -3 is -5 and 2-4 is -2 so y equals -5/2x plus b. I put in 2,-2 into the equation to get the y intercept, so 2 equals -5/2 times 2 plus b -5/2(2) is -10/-4 reduce to -5/-2 Now add

    asked on September 26, 2009
  81. physics

    Determine the elongation of the rod in if it is under a tension of 5.7E10^3 N. The rod is made of aluminum and copper. From the aluminum to the copper section it measures 1.3m and from the copper section to the end it measures 2.6m with a radius of 0.2cm.

    asked on July 21, 2008
  82. Physics

    There is a parabolic position vs time graph. Which of these is true: The object moves 1. in a parabolic trajectory. 2. along a straight line. 3. along an arc of a circle wouldn't 1 and 3 produce the same/similar position graph?

    asked on June 4, 2008
  83. physics

    1. It has been suggested that rotating cylinders about 11 mi long and 5.2 mi in diameter be placed in space and used as colonies. What angular speed must such a cylinder have so that the centripetal acceleration at its surface equals the free-fall

    asked on July 11, 2008
  84. algebra

    At 3:00 pm the temperature was 2* below zero. It then fell 4* in the next 2 hours. what was the temperature at 5:00pm?

    asked on August 8, 2013
  85. algebra

    A 125-ft diagonal brace on a bridge connects a support of the center of the bridge to a side support on the bridge. The horizontal distance that it spans is 25 ft longer than the height that it reaches on the side of the bridge. Find the horizontal and

    asked on June 19, 2011
  86. algebra

    Use the “difference of squares” rule to factor the following expression: 100a^6-64b^8

    asked on June 19, 2011
  87. algebra

    Megan factored the expression 72x^2-43x+6 as (9x-3)(8x-2). But when Jacob applied the FOIL principle and multiplied out (9x-3)(8x-2), he got72x^2-42x+6; thus, Megan’s solution does not appear to check. Why is that? Please help Megan to understand this

    asked on June 19, 2011
  88. algebra

    Factor out the greatest common factor from the expression 9a2b3 – 12a2b4 – 24a3b

    asked on June 19, 2011
  89. algebra

    Factor the expression 16x^2-72xy+81y^2 into a product of binomials.

    asked on June 19, 2011
  90. Intermediate Algebra

    Factor completely. If a polynomial is prime, state this 9 + 8t^2 - 18t

    asked on June 17, 2011
  91. algebra

    Graphthe equation y plus 6 equals 1/8(x-2 1/8x - 2/8 add 2/8 to 6, so 61 times 8/8 makes it 48/8 plus 2/8 is 50/8 mx plus c would be 1/8 plus 50/8. Is this correct so afr? If so how do I graph 50/8? Do I just put at 50 on the y axis and do 1/8 rise over

    asked on September 27, 2009
  92. algebra

    Write an equation of a line that passes through the points (-6,7) and has a slope of -4 How do I do this? it would be y equals -4x but not sure how to do the rest.

    asked on September 26, 2009
  93. Algebra

    How come (2xy^2)^3 is equal to 8x^3 y-6? I thought that six exponent should be a five since you add them together. So 2 and 3 should be five. But why is this?

    asked on September 12, 2009
  94. math

    Hi! I have a question Heres the problem: 3-2[6-(4y-1)] I got -8y-11 but it wasn't right and I don't know what i did wrong help please!

    asked on August 16, 2009
  95. physics: drwls

    drwls for the question below, the answer seems to be wrong: The four tires of an automobile are inflated to a gauge pressure of 1.8 multiplied by 105 Pa. Each tire has an area of 0.025 m2 in contact with the ground. Determine the weight of the automobile.

    asked on July 22, 2008
  96. Physics

    How does an electric motor work, linking to the theory of electromagnetism? I have already identified a few laws: -Ohms -Faraday's

    asked on October 24, 2015
  97. Algebra 2

    Solve Quadratic System x^2+y^2=2 x^2-6y=10 Please show work!!!

    asked on November 23, 2014
  98. math

    Simplify the expression. 5(x − 1) − 3(x^2 + 4x + 5)- 8(x+7)=

    asked on October 21, 2013
  99. math

    please help simplify 5(x-1) - 3(x^2 + 4x + 5) - 8(x + 7)

    asked on October 20, 2013
  100. algebra

    The length of a rectangle is 2 meters more than its width. If the area is 63 square meters, what are the length and width?

    asked on June 19, 2011

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