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Physics Questions

Discussion in 'MCAT Study Question Q&A' started by FedExpress85, 02.14.13.

  1. FedExpress85

    FedExpress85

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    For some stupid reason, I'm stuck on these questions (some of them pretty basic) It's been a while since I've done physics. Any help would be greatly appreciated!

    1. A satellite weighs 104 N at ground control. What best approximates the acceleration it experiences in orbit at an altitude of twice the earth’s radius?

    A. 111 m/s2
    B. 2.5 m/s2
    C. 1.1 m/s2
    D. 0 m/s2

    2. The sun is approximately 150 million kilometers from the earth. A year—the time for one revolution of the earth around the sun—is roughly π × 107 seconds. Assuming a circular orbit, what best approximates the average acceleration of the earth due to the sun?

    A. 6 × 10–6 m/s2
    B. 6 × 10–3 m/s2
    C. 6 × 102 m/s2
    D. 4 × 1019 m/s2

    3. A rectangular book weighing 20 N with sides of 10 cm and 20 cm is placed on a horizontal table. Using each of your hands, you exert forces of 10 N each in opposite directions at opposite corners, such that you are pushing parallel to the shorter side in each case. What net torque are you providing to the book?

    A. 0 N-m
    B. 0.5 N-m
    C. 1 N-m
    D. 2 N-m

    4. A hammer head with a mass of 500 g moving at 4 m/s collides with a nail (m = 4 g) and comes to a stop in 0.002 seconds. What average force acts on the nail during that time?

    A. 106 N
    B. 103 N
    C. 8 N
    D. 8 ×103 N

    5. A solid plastic cube with uniform density (side length = 0.5 m) of mass 100 kg is placed in a vat of fluid whose specific gravity is 1.2. What fraction of the cube’s volume floats above the surface of the fluid?

    A. 1/5
    B. 1/3
    C. 2/3
    D. 4/5

    6. An object with mass 30 kg and specific gravity 3.6 is placed in a fluid whose specific gravity is 1.2. Neglecting viscosity, which of the following is true?

    A. The acceleration of the object is (1/3)g and its apparent weight is 100N
    B. The acceleration of the object is (2/3)g and its apparent weight is 100N
    C. The acceleration of the object is (1/3)g and its apparent weight is 200N
    D. The acceleration of the object is (2/3)g and its apparent weight is 200N

    7. A fluid of density ρ flows through a horizontal pipe with negligible viscosity. The flow is streamline with constant flow rate. The diameter of the pipe at Point 1 is d and the flow speed is v. If the diameter of the pipe at Point 2 is d/3, then the pressure at Point 2 is:

    A. Less than the pressure at Point 1 by 4ρv
    B. Less than the pressure at Point 1 by 40ρv
    C. More than the pressure at Point 1 by 4ρv
    D. More than the pressure at Point 1 by 40ρv

    8. An ideal fluid flows through a pipe with radius R with flow speed v. If the pipe splits up into three separate paths, each with radius (R/2), what is the flow speed through each of the paths?

    A. v/3
    B. 2v/3
    C. 4v/3
    D. 4v

    9. Traveling at an initial speed of 1.5 x 106 m/s, a proton enters a region of constant magnetic field of magnitude 1.5 T. If the proton’s initial velocity vector makes an angle of 30° with the magnetic field, compute the proton’s speed 4 s after entering the magnetic field.

    A. 5.0 × 105 m/s
    B. 7.5 × 105 m/s
    C. 1.5 × 106 m/s
    D. 3.0 × 106 m/s

    10. Consider two adjacent transparent media. The speed of light through Medium 1 is v1, and the speed of light through Medium 2 is v2. If v1 < v2, then total internal reflection will occur at the interface between these media if a beam of light is

    A. incident in Medium 1 and strikes the interface at an angle of incidence greater than arcsin(v1/v2)
    B. incident in Medium 1 and strikes the interface at an angle of incidence greater than arcsin(v2/v1)
    C. incident in Medium 2 and strikes the interface at an angle of incidence greater than arcsin(v1/v2)
    D. incident in Medium 2 and strikes the interface at an angle of incidence greater than arcsin(v2/v1)
  2. Ibn Alnafis MD

    Ibn Alnafis MD

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    First of all, you need to provide us with the answers so we know we are on the right track.

    Second, how do you expect to learn problem solving if you don't even provide us with your thought process and the reasons why you are not being able to come up with the right answer so we could point you in the right direction?

    Third, I don't think many have the time to type out the solutions to all ten questions.
  3. FedExpress85

    FedExpress85

    Joined:
    02.04.13
    Messages:
    11
    I don't have the answers.

    Sorry, I forgot to include my thought process. Here it is.

    <A satellite weighs 104 N at ground control. What best approximates the acceleration it experiences in orbit at an altitude of twice the earth's radius?>

    galt/gsur= (GM/r^2)/(GM/R^2)= (1/3)^2 * g= 1/9* 9.8= 1.1

    So I got C.

    A solid plastic cube with uniform density (side length = 0.5 m) of mass 100 kg is placed in a vat of fluid whose specific gravity is 1.2. What fraction of the cube's volume floats above the surface of the fluid?

    Vsub/V= pobject/pfluid
    = 100kg/.125m^3= 8000 kg/m^3 = pobject

    = 800/1200
    = 2/3

    Since 2/3 is submerged, that means 1/3 is above the surface of the liquid. So I got B.
  4. Ibn Alnafis MD

    Ibn Alnafis MD

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    I just tried to solve those two problems and got the same answers you got. It seems you're on the right track, unless I'm wrong.

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