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Kinematic equations problems

5 kinematic equations:

Kinematics is the branch of mechanics dealing with the motion of bodies without reference to mass or force.There are three basic equations of motion for bodies moving with uniform acceleration.These equations relate initial velocity,final velocity,acceleration,time and distance covered by a moving body.To simplify the derivation of these equations,we assume that the motion is along a straight line.Hence,we consider only the magnitude of displacements,velocities,and acceleration.

First equation of motion:

Consider a body moving with initial velocity Vi in a straight line with uniform acceleration a.Its velocity becomes Vf after time t.The motion of body is described by speed time graph represented by line AB.The slope of line AB is acceleration a.The total distance covered by the body is shown by the shaded area under the line AB.Kinematic equations of motion can be obtained easily from this graph.

speed time graphSpeed time graph for the motion of a body is shown in figure.Slope of line AB gives the acceleration of a body.

first equation of motion

Second equation of motion:

Consider a body is moving with initial velocity ‘Vi’ in a straight line with uniform acceleration ‘a’.Lets its velocity becomes ‘Vf’ after time t.The motion of body is described by speed time graph by the line AB as shown in figure below.The total distance ‘S’ is covered by the body is equal to the total area OABD under the graph.

speed time graph

second equation of motion

It is known as 2nd equation of motion.

Third equation of motion:

Consider a body moving with initial velocity ‘vi’ in a straight line with uniform acceleration ‘a’.Let its velocity becomes Vf after time ‘t’.The motion of body is described by speed time graph as shown in figure by line AB.The total distance ‘S’traveled by the body is given by the total area OABD under the graph.

kinematics equation

third equation of kinematics

It is 3rd equation of motion.

The conditions under which these equations can be applied:

1:Motion should be 1-dimensional.

2:Acceleration should be uniform.

3:Frame of reference should be inertial.

Problem solving by kinematic equations:

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