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  1. M

    Archimedes' principle

    Homework Statement A rectangular waterproof air mattress is 2.0m long, 0.50mwide and 0.08m thick. It has a mass of 2.0kg and is supporting an additional mass of m, while floating in the water, calculate the mass, m, assuming the density of water is 1000kg/m^3 and density of air is...
  2. M

    Spring compression help

    Homework Statement A 0.40kg object connected to a light spring with a force constant of 19.6N/m oscillates on a frictionless horizontal surface. If the spring is compressed 4.0 cm and released from rest, determine (a) the maximum speed of the object. Homework Equations F = -kx The...
  3. M

    Heat and internal energy of water temperature

    Homework Statement Water at the top of Niagara Falls has a temperature of 10.0degrees celsius. If it falls a distance of 50.0m and all of its potential energy goes into heating the water, calculate the temperature of the water at the bottom of the falls. Homework Equations W = change...
  4. M

    Use conservation of energy to determine the angular speed of a spool

    Homework Statement Use conservation of energy to determine the angular speed of a spool after the bucket(3.0kg) has fallen 4.00m, starting from rest. Homework Equations KE = 1/2mv^2 KEr = 1/2 * I * omega^2 PE - mgh The Attempt at a Solution i don't know how to start. I...
  5. M

    Simple problem, but confused with acceleration of gravity

    Homework Statement A silo is under construction and a large brick is being hoisted up at a constant speed of 3.2m/s. The rope breaks when the brick is at a height of 28m above the ground. a) find the greatest height reached by the brick. Homework Equations i know which equation to...
  6. M

    Need clarification about x-t and v-t graph

    Homework Statement I'm confused with what a negative slope means on an x-t and v-t graph. On an x-t graph, I understand that a positive constant slope means uniform velocity and when the slope is 0, then the object is stationary. On a v-t graph, constant slope means constant acceleration...
  7. M

    Latent heat and phase change question

    Homework Statement A 100g cube of ice at 0 degrees is dropped into 1.0kg of water that was originally at 80 degrees. What is the final temperature of the water after the ice has melted? Homework Equations Q = ml Q = mc(Tf - Ti) The Attempt at a Solution i'm not sure again about...
  8. M

    Please help calorimetry problem

    Homework Statement What mass of ice at -10.0 degrees celsius is needed to cool a whale's water tank, holding 1.20 x 10^3 m^3 of water, from 20.0 degrees down to a more comfortable 10 degrees. Homework Equations Q = mc *delta T Q = mL The Attempt at a Solution i'm trying to...
  9. M

    How much of an iceberg is beneath the surface Archimedes principle

    How much of an iceberg is beneath the surface....Archimedes principle Homework Statement Calculate how much of an iceberg is beneath the surface of the ocean, given that the density of ice is 917kg/m^3 and salt water has density 1025kg/m^3. Homework Equations archimedes principle...
  10. M

    Going down a slide CONSERVATION OF ENERGY

    Homework Statement Suppose a slide is 35.0 meters high, but is a straight slope, inclined at 45 degrees with respect to the horizontal. a) find the speed of a 60.0kg thrill seeker at the bottom of the slide, assuming no friction. b) if the thrill seeker has a speed of 20.0m/s at the...
  11. M

    Need help with finding angles RE: finding vector components

    Homework Statement See attached photo. Find the resultant displacement measured from the starting point. Homework Equations The Attempt at a Solution When it comes to angles, i sometimes get confused when to add 180 or not. FOr the first two distances, we don't have to find...
  12. M

    Graph of simple harmonic motion

    Homework Statement A particle moves with amplitude A and period T (see figure). Express the following in terms of A and T and numberical constants. a) The time at which the phase is pi/2 b) maximum v c) max a d) time at which acceleration is a maximum Homework Equations The...
  13. M

    Question involving conservation law and springs!

    Homework Statement A freight car of mass 1800kg is timed at 4.2m/s just after it runs into a spring-loaded bumper at the end of the track. The bumper consists of an 800kg mass that the car runs into, and a pair of large springs. The car travels 2.4m before coming to rest. a)using an...
  14. M

    Tuning fork and resonances

    Homework Statement A tuning fork is held over the top of a graduated cylinder that is slowly filled with water. Resonances are noted when the water level is 56.5cm and 17.5cm below the rim. Note that there is an end correction , meaning that the effective length of the air column is longer...
  15. M

    Calculate difference between observed frequency and original frequency

    Homework Statement A radar trap operates at a frequency of f = 10GHz. The speed of microwaves is 3.0x10^8m/s. The microwave beam is aimed at a car approaching at 20m/s. a) calculate difference between observed frequency and original frequency. b) the car becomes the moving source at...
  16. M

    Kinematics: simple harmonic motion

    Homework Statement The motion of a particle is given by x=(6.0m) cos(0.586t +0.72) a) find amplitude b) find period c) find the first time for t>0 when v=0 d) find the max acceleration e) find the phase at time t = 1.38s Homework Equations T = 2pie/omega v = -A omega sin omega*t...
  17. M

    Concept about double glazed windows

    Homework Statement Double glazed windows are usually made of two glass panes with a thin layer of air sealed between the panes. a) Why do these windows reduce heat loss to a much great extent than occurs if the double glazing is replaced by a thicker glass instead? b) Why does the insulating...
  18. M

    Concept question about testing antifreeze

    Homework Statement A simple device that is used to test the strength of antifreeze in cars consists of a small tube that has several small, coloured spheres inside it. When antifreeze is admitted into the tube, some of the spheres will float, giving an indication of the strength of the...
  19. M

    Linear expansion

    Homework Statement A glass tube of radius 0.80cm contains liquid mercury to a depth of 64.0cm at 12degrees. Find the depth of the mercury column at 100degrees. Assume that the linear expansion coefficient of the glass is 10x10^-6K-1 and the linear expansion coefficient of mercury is...
  20. M

    Density and Volume

    Homework Statement A balloon is to be filled with helium(density = 0.178kg/m^3) while the air outside has density of 1.29km/m^3. The mass of the empty balloon is 80.0kg and it is to lift a load of 240kg. What minimum volume is necessary for the lift off? Assume that the balloon material and...
  21. M

    Energy Transfer

    Homework Statement A space station in outer space has a total surface area of 580m^2 with emissivity of 0.62. The temperature of the outside surface is 156K. The walls are 0.25m thick with an average thermal conductivity of 0.038W/mK. Find the temperature of the inner wall of the space...
  22. M

    Rotational Kinetic energy

    Homework Statement A horizontal 800N merry go round of radius 1.50m is started from rest by a constant horizontal force of 50.0N applied tangetially to the merry go round. Find the kinetic energy of the merry go round after 3.00s. (assume it is a solid cylinder). Homework Equations I =...
  23. M

    Simple torque question

    Homework Statement A fishing pole is 2.00m long and inclined to the horizontal at an angle of 20.0degrees. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the hand of the person holding the pole? Homework Equations The Attempt at...
  24. M

    Calorimetry homework help

    Homework Statement A copper container of mass 0.080kg and specific heat of 387Jkg-1K-1 contains 0.30kg of water and 0.040kg of ice at 0degrees. Steam at 100 degrees is passed into the water and its temperature stabilizes at 20.0degrees. Find the mass of the water left in the container...
  25. M

    Energy transfer

    Homework Statement A block of material with a cross sectional area of 15cm^2 and length of 8cm is at hand. A temperature difference of 30degrees is established and maintained across the block. Find the rate of heat flow through it if the material is wood (K = 0.08Js-1m-1C-1) Homework...
  26. M

    Simple torque problem

    Homework Statement A man ties one end of a strong rope 8.00m long to the bumper of his truck, 0.500 from the ground, and the other end to a vertical tree trunk at a height of 3.00m. He uses the truck to create a tension of 8.00x10^2N in the rope. Compute the magnitude of the torque on the...
  27. M

    Are astronauts weightless in orbit?

    Homework Statement If someone told you that astronauts are weightless in orbit because they are beyond the pull of gravity, would you accept this statement? Explain. Homework Equations The Attempt at a Solution I say no. There is still gravity, but its just weaker with distance...
  28. M

    Angular velcoity of point masses

    Homework Statement The system of point masses m shown in the above figure is rotating at an angular velocity of 2rev/s. The masses are equal and connected by light flexible spokes that can be lengthened or shortened. What is the new angular velocity if the spokes are shortened from 1m to...
  29. M

    Torques and angular rotation

    torques and angular rotation.... [b]1. Homework Statement [/b a grindstone used to sharpen tools is rotating at an angular speed of 8 rad/s when an axe is pressed against it. because of the torque produced on the grindstone by the force of friction between it and the axe, it comes to rest in...
  30. M

    Please help rotational motion

    Please help....rotational motion Homework Statement A stuntman swings from the end of 4 m long rope along the arc of a vertical circle. If his mass is 70kg, find the tension in the rope required to make him follow his circular path, assuming he starts from rest when the rope is horizontal...
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