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KINEMATIC EQUATIONS

     Thepurpose of this web site is to teach or help you interested readers tobetter understand the first two kinematic equations of Physics. Hopefullyyou will understand how to use these equations to solve problems and applythem to real life applications. I will give several example problems, explainsimilar equations and provide links to other pages with kinematics.

Real Life Applications

-    any sport that involves an object being moved
-    vehicles moving
 

Equations

V = Vo + at - First KinematicEquation
x = ½ (Vo + V)t - SecondKinematic

V = final velocity - metersper second (m/s)
Vo = initial velocity -meters per second (m/s)
a  = acceleration - metersper second squared (m/s²)
t = time - seconds (s) x = distance - meters (m)
 

    These two equationscan be used to find the final velocity, initial velocity, acceleration,time and distance of any moving object. All you have to know is which numbersand units to plug in each variable of the equation. From there it is merelysimple algebra to solve each equation. The hardest part is just determiningwhich equation to use. The only difference though is that the first equationhas acceleration in it and the second has distance.

Example Problems
1. John is driving a car with aninitial velocity of 24m/s and it hits a brick wall in 3.3s. How far didhe travel?

x = ½(V + Vo)t
x = ½(0 + 24m/s)3.3s
x = 39.6m

2. Kelly launches a rocket intothe air and it takes 2.3s to come back down to the ground. How far didthe rocket travel?

V = Vo + at
0 = Vo + (-9.8m/s²)(2.3s)       -9.8m/s = gravity
Vo = 22.54m/s

x = ½(V + Vo)t
x = ½(0 + 22.54m/s)(2.3s)
x = 25.921m

3. Rob shoots a bullet 112m/s witha final velocity of 43m/s. If it took 6s to get there what was the acceleration?

V = Vo + at
43m/s = 112m/s + a(6s)
a = 43/6 - 112
a = - 104.833m/s²

Related Formulas
Second Two Kinematic Equations:
x = Vot + ½at ²
V² = Vo² +2ax

V = final velocity - metersper second (m/s)
Vo = initial velocity -meters per second (m/s)
a  = acceleration - metersper second squared (m/s²)
t = time - seconds (s) x = distance - meters (m)

    The second twoKinematic equations are basically just different versions of the firsttwo but solve for the answers differently. Sometimes the second two aremore efficient but they're usually not.These four Kinematic equations alsohelp to partially solve projectile motion problems. Projectile motion isan object being launched at some angle and velocity. Unfortunately thatalso involves using a few more unrelated formulas just to solve one ofthose formulas.

Links
Click herefor my other physics page
Click herefor a physics page on the other Kinematic Equations
Click herefor physics page on the Cardinal directions

 

Copyright Robby Warren 2001