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    Stargazing Question on Refractor Telescope !

    I am plan on building a small refractor telescope about 20 cm long, i need your guys help ! 1. What len is use for Objective len and what len is use for Eyepiece len ? (how is it look like) 2. How far should i place objective len and eyepiece len apart ? 3. If i make a 20 cm long refractor...
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    KE and PE Work

    #1 A 10kg crate is pulled up a rough incline with an initial speed of 1.5 m/s. The pulling force is 100Nparallel to the incline, which makes an angle of 20* with the horizontal. If the coefficient of kinetic friction is .40 and the crate is pulled a distance of 5 m. a)HOw much work is done by...
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    Acceleartion and Force again !

    #1 Ricky is on a rocket ship far from any planet or sun. The 900kg rocket fires its rockets for 3.5s sec and goes from 0m/s to 50 m/s.(a)What acceleration does the rocket undergo ?(b) If 160 kg of gas is expelled from the rocket. what is the gasses acceleration ? ------------------ vi = 50...
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    Acceleration coefficient

    Find the acceleration experienced by each of the two masses shown in the picture below if the coefficient of friction between the 7 kg mass and the plane is .25 ? ------------ In the picture, is the force of fiction go that way ? [Broken]...
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    Coefficient of friction of box of books

    Problem 1: A box of books weighting 300 N is shoved cross the floor of an apartment by a force of 400 N exerted downward at an angle of 35.2* below the horizontal. If the coefficient of kinetic friction between box and floor is .57, how long does it take t move the box 4 m, starting from rest ...
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    Force - Scale - Tension

    #1 On takeoff, the combined action of the engines and wings of an airplane exerts an 8000N force on the plane, directed upward at an angle of 65* above the horizontal. The plane rises with constant velocity in the vertical direction while continuing to accelerate in the horizontal direction...
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    What force ?

    #1 A 5 g bullet leaves the muzzle of a rifle with a speed of 320 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the .82 m long barrel of the rifle ? -------------------------- m = .005 kg v (initial) = 320 m/s d = .82m F = ma but i don't know how to find...
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    Magnitude - Distance

    [SOLVED] Magnitude - Distance #1 The force of the wind on the sails of a sailboat is 390 N north. The water exerts a force of 180 N east. If the boat (including crew) has a mass of 270 kg, what are the magnitude and direction of its acceleration. --------------------------------- 390 N...
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    The Law of Motion

    An 850 kg car is moving to the right at 1.44 m/s. What is the net force on the car ? I am totally off on this problem ! Can someone help ? And in the problem above, it is different when the car moving left ? Thanks
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    2 Projectile Motion Problem

    #1 A bullet traveling 800 m/s horizontally hits a target 180 m away. How far does the bullet fall before it hits the target ? --------------------------------------- My work: X d = 180 m Vx = 180 m/s t = .225 s Y a = -9.8 m/s2 t = .225 s (time in x direction = time in y direction)...
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    Projectile Motion of a thrown stone

    Homework Statement #1 A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 18 m/s. The cliff is 50 m above a flat horizontal beach. How long after being released does the stone strike the beach below the cliff ? With what speed and angle of...
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    Vector help please

    Homework Statement #2 Two people pull on a stubborn mule, as seen from a helicopter in Figure 1. Find (a) the single force that is equivalent to the two forces shown, and (b) the force that a third person ould have to exert on the mule to make the net force equal to zero. Figure 1...
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    How long does it take ?

    Homework Statement A hockey player is standing on his skates on a frozen pond when an opposing player, moving with a uniform speed of 12 m/s, skates by with they puck. After 3.0s, the first player makes up his mind to chase his opponent. If he accelerates uniformly at 4.0 m/s2. How long does...
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    About my career

    I am planning to persuade the Computer Hardware Engineer career. And I also planning to work in CA(San Jose) or AZ(Phoenix). So i wonder will you get a good pay ? Is there a big chance that i will be laid off.
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    A ball throw up and down !

    Homework Statement #1 a) A ball is throwing straight upward, Is that motion positive or negative acceleration/velocity/displacement ? b) A ball is falling down (what go up must come down), Is that a positive or negative acceleration/velocity/displacement ? #2 a) A car is moving forward...
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    Motion in One Dimension

    Homework Statement #1 Runner A is initially 4.0 mi west of a flagpole and is running with a constant velocity of 6.0 mi/h due to east. Runner B is initially 3.0 mi east of the flagpole and is running with a constant velocity of 5.0 mi/h due west. How far are the runners from the flagpole...