What Are Some Basic Physics Equations for Calculating Motion and Energy?

[toljin]

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 <-- can't figure this out :/

2) 10 * 8 = 80 m/s

3) again I can't seem to figure this out

4) g = 2(45m)/3s^2 = 10ms^-1

 

[UltrafastPED]

(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.

 

[NihalSh]

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) = 2m2) Calculate the momentum of a mass of 10kg when its velocity is 8ms-13) 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.

 

[NihalSh]

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.

 

[toljin]

thanks I knew that I would have to integrate number one, Did I get the displacement right on number 1?