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Physics Formulas

  1. Oct 16, 2013 #1
    Basic Physics

    First post so be gentle :). I have a couple of questions :)

    1) The acceleration of a body is given by a(t) = 4t3 + 3ms-2. Find its velocity and displacememt if v(1) = 0ms-1 and x(1) = 2m

    2) Calculate the momentum of a mass of 10kg when its velocity is 8ms-1

    3) An object of mass 5kg moves from rest with an acceleration of 0.15ms-2 calculate its velocity,displacement and kinetic energy 10 seconds later.

    4) In an experiment to determine the acceleration due to gravity you drop a dall bearing, from rest, through a vertical distance of 45m and find it takes 3 seconds to reach the ground.Calculate the acceleration due to gravity and your weight.

    3. The attempt at a solution

    1) Displacement = x(1) = 2m - initial position which is = 0 so displacement = 2m
    Velocity = displacement/time <-- cant figure this out :/

    2) 10 * 8 = 80 m/s

    3) again I cant seem to figure this out

    4) g = 2(45m)/3s^2 = 10ms^-1
  2. jcsd
  3. Oct 16, 2013 #2


    User Avatar
    Science Advisor
    Gold Member

    (1) For the velocity you integrate the acceleration; a = dv/dt.

    (2) You must also provide the units!

    (3) Use the constant acceleration of gravity near the surface of the earth.
  4. Oct 16, 2013 #3
    I believe your acceleration function is ##a(t)=4.t^3+3##, in SI units. you'll have to integrate the acceleration function to obtain velocity function. To evaluate constant of integration, use the given information.
  5. Oct 16, 2013 #4
    Check the units what should be the unit of momentum. you are multiplying mass and velocity.

    you have been given acceleration, if the acceleration is constant which equations should be applied???.....Think, try to recall.

    Again check your units.
  6. Oct 16, 2013 #5
    thanks I knew that I would have to integrate number one, Did I get the displacement right on number 1?
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