In the given figure, the distance travelled (s) by a body in time (t) is given by the area of the figure OABC which is a trapezium.Distance travelld = Area of the trapezium OABCSo, Area of trapezium OABC,= `"(Sum of parallel sides)(Height)"/2`=`"(OA+CB)(OC)"/2`Now, (OA + CB) = u + v and (OC) = t.Putting these values in the above relation, we get:`s = ((u+v)/2)t` ....(1)Eliminate t from the above equation. This can be done by obtaining the value of t from the first equation of motion.v = u + atSo,`t = "v-u"/a`Now, put this value of t in equation (1), we get: `s = (((u+v)(v-u))/(2a))`On further simplification, 2as = v2 – u2 Finally the third equation of motion.`v^2 = u^2 + 2as`where(s) - Displacement(u) - Initial velocity(a) - Acceleration(v) - Final velocity(t) - Time taken Equations of motion of kinematics describe the basic concept of the motion of an object such as the position, velocity or acceleration of an object at various times. These three equations of motion govern the motion of an object in 1D, 2D and 3D. The derivation of the equations of motion is one of the most important topics in Physics. In this article, we will show you how to derive the first, second and third equation of motion by graphical method, algebraic method and calculus method. Equations of motion, in physics, are defined as equations that describe the behaviour of a physical system in terms of its motion as a function of time. There are three equations of motion that can be used to derive components such as displacement(s), velocity (initial and final), time(t) and acceleration(a). The following are the three equations of motion: \(\begin{array}{l}v=u+at\end{array} \) \(\begin{array}{l}s=ut+\frac{1}{2}at^2\end{array} \) \(\begin{array}{l}v^2=u^2+2as\end{array} \) To brush up on the basics of motion, refer to the article listed below::
The equations of motion can be derived using the following methods:
In the next few sections, the equations of motion are derived by all the three methods in a simple and easy to understand way.
For the derivation, let us consider a body moving in a straight line with uniform acceleration. Then, let the initial velocity be u, acceleration is denoted as a, the time period is denoted as t, velocity is denoted as v, and the distance travelled is denoted as s.
We know that the acceleration of the body is defined as the rate of change of velocity. Mathematically, acceleration is represented as follows: \(\begin{array}{l}a=\frac{v-u}{t}\end{array} \) where v is the final velocity and u is the initial velocity. Rearranging the above equation, we arrive at the first equation of motion as follows:
The first equation of motion can be derived using a velocity-time graph for a moving object with an initial velocity of u, final velocity v, and acceleration a. In the above graph,
The following details are obtained from the graph above: The initial velocity of the body, u = OA The final velocity of the body, v = BC From the graph, we know that BC = BD + DC Therefore, v = BD + DC v = BD + OA (since DC = OA) Finally, v = BD + u (since OA = u) (Equation 1) Now, since the slope of a velocity-time graph is equal to acceleration a. So, a = slope of line AB a = BD/AD Since AD = AC = t, the above equation becomes: BD = at (Equation 2) Now, combining Equation 1 & 2, the following is obtained:
Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin! Select the correct answer and click on the “Finish” button
Visit BYJU’S for all Physics related queries and study materials
0 arewrong out of 0 are correct out of0 are Unattempted View Quiz Answers and Analysis out of |