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Physics Formulas

  • Thread starter toljin
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  • #1
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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.



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
 

Answers and Replies

  • #2
UltrafastPED
Science Advisor
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(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.
 
  • #3
199
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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.
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.
 
  • #4
199
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2) 10 * 8 = 80 m/s
Check the units what should be the unit of momentum. you are multiplying mass and velocity.

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

4) g = 2(45m)/3s^2 = 10ms^-1
Again check your units.
 
  • #5
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thanks I knew that I would have to integrate number one, Did I get the displacement right on number 1?
 

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