How to Derive the Formula for Kinetic Energy: 10 Steps
Step 1: Understand the Basics of Kinetic Energy
Kinetic energy is the energy that an object possesses due to its motion. It is directly proportional to both the mass of the object and the square of its velocity.
Step 2: Define Variables
Let’s define m as the mass of an object and v as its velocity. Our goal is to derive a formula for kinetic energy (K) in terms of these variables.
Step 3: Recall Newton’s Second Law of Motion
According to Newton’s Second Law, force (F) acting on an object is equal to its mass (m) multiplied by its acceleration (a):
F = ma
Step 4: Calculate Work Done
Work (W) done on an object can be defined as the force (F) applied to it, multiplied by the displacement (d) in the direction of force. In this case:
W = Fd
Step 5: Combine Newton’s Second Law and Work Done Formula
By combining F = ma from step 3 with W = Fd from step 4, we get:
W = mad
Step 6: Express acceleration in terms of velocity and displacement
Acceleration can be described as the change in velocity over time or, in this case, over distance travelled. Therefore, we can write acceleration (a) as follows using a kinematic equation:
v^2 = u^2 + 2ad
where v represents final velocity, u represents initial velocity and a represents acceleration.
Since kinetic energy is associated with movement, we will consider initial velocity u as zero. So:
v^2 = 2ad
Step 7: Isolate ‘ad’
From step 6, we can solve for ad by dividing both sides of the equation by 2:
ad = v^2/2
Step 8: Substitute ‘ad’ back into the expression for Work
Using the relationship found in step 7, substitute v^2/2 for ad in our equation for work (W):
W = m(v^2/2)
Step 9: Define Kinetic Energy
Kinetic energy (K) is equivalent to the work done on an object in motion. Thus, based on step 8, we can say:
K = W
Step 10: Derive the Formula for Kinetic Energy
Finally, equating K and W from step 9, we get the formula for kinetic energy:
K = mv^2/2
And there you have it! The formula for kinetic energy (K) can be derived in 10 relatively simple steps. Now you can use this powerful formula to analyze an object’s energy due to its motion.