 Myself, Mr. A. N. Suvade, Assistant Professor, Department of Mechanical Engineering, from Walshchan Institute of Technology, Sholapur, today we are going to study acceleration in a mechanism. Learning outcome at the end of this lecture, student will be able to draw and determine acceleration diagram for a given mechanism by relative velocity method. So, in the last session, we have discussed about the velocity diagram and from the velocity diagram, we have determined the velocity of B with respect to O as well as relative velocity of AB that is 3.4 meter per second, slider velocity VA 4 meter per second and velocity of midpoint 4.1 meter per second. And now we are going to discuss about the acceleration diagram. So, first of all, for drawing the acceleration diagram, we have to calculate the radial component of acceleration for various links. So, here first of all, we will calculate the radial component of B with respect to O that is equal to V square BO divided by link length BO. So, velocity of B with respect to O is 4.713 square divided by link length OB that is 0.15 and this will be equal to 148.1 meter per second square. Similarly, acceleration of A with respect to B that will have two components. One is tangential component of acceleration and other is radial component of acceleration. So, radial component of AB that will be equal to V square AB divided by link length AB. So, velocity of A with respect to B is 3.4 bracket square divided by link length AB 0.6 meter and that is equal to 19.3 meter per second square. So, in this particular table, we will put the values which we have calculated. So, radial component of B with respect to A 148.1 and radial component of AB 19.3 meter per second square. And now, with certain suitable scale, we will start to draw the acceleration diagram. So, take certain suitable scale. In this case, 1 centimeter is equal to 19.3 meter per second square. This is my scale for acceleration diagram. Now, in this case, the link BO, it is rotating with constant angular speed. So, here think for a while a link which rotates with constant speed whether it has both components of acceleration. So, the link which rotates with constant angular speed, it will have only radial component of acceleration because dV by dt is 0 and therefore, its tangential component of acceleration is 0. And therefore, tangential component of B with respect to O is 0 because link OB rotates with constant angular speed. And now, with this we will draw acceleration diagram. So, first of all, take a point O dash as a fixed point in space. So, mark point O dash as a fixed point. Now, acceleration of B with respect to O, it has only one component of acceleration that is radial component of acceleration whose magnitude is 148.1 meter per second square. And as we know, the radial component of acceleration will always act parallel to link OB and towards the centre. And hence, from point O dash, draw a vector parallel to OB which will represent the magnitude as well as the direction of radial component of acceleration of B with respect to O. So, this vector O dash B dash will represent the radial component of B with respect to O. Its tangential component is 0. And now, we will move further for link AB. So, link AB will have two components of acceleration. One is radial component and second is tangential component. Radial component of AB we have determined the magnitude. But at this moment, the tangential component of AB is unknown. So, from point B dash, draw a vector B dash x parallel to link AB which will represent the radial component of AB in magnitude and direction. So, the vector B dash x will be parallel to AB and it is towards the centre that is towards point B. So, from vector B dash in the acceleration diagram, draw a vector B dash x parallel to AB. So, this vector B dash x, this vector will represent the radial component of A with respect to B. And now, its tangential component is unknown. But we can determine the direction of tangential component of acceleration. So, radial component and tangential components are perpendicular to each other or tangential component of A with respect to B that will be always a perpendicular to link AB. So, from point X, draw a vector perpendicular to radial component of AB or perpendicular to link AB. At this moment, we do not know magnitude. Hence, we have to just draw the vector. And now, acceleration of point A, linear acceleration of point A as the slider A slides along the line of reciprocation OA. Hence, from point O dash, draw a vector parallel to path of reciprocation. So, these two vectors will intersect each other at point A dash. And therefore, vector x A dash will represent the tangential component of AB and vector O dash A dash will represent the acceleration of slider A. Now, vector A dash B dash that will represent the total acceleration of link AB. So, radial component of AB and tangential component of AB are perpendicular to each other. Now, in the space diagram, the point D is the midpoint of AB. And similarly, here also, the vector D dash will lie on vector A dash B dash. So, as the point D divides the link AB, the ratio in which the point D divides the link AB in the same ratio, vector D will divide the vector A dash B dash. And hence, by using the equation A dash D dash divided by vector A dash B dash is equal to link length AD divided by link length AB. So, we have to mark the vector D dash from A dash. So, this is unknown to you. So, put the value of AD AB and measure the vector A dash B dash and calculate the vector length A dash D dash. So, here, I will just measure the vector A dash B dash. This will be 5.4. So, it will be half of 5.4. So, just mark the point D dash on vector A dash B dash as D is midpoint of AB, D dash will be midpoint of vector A dash B dash. And then, join O dash D dash. So, this vector O dash D dash will represent the acceleration of point D. So, in this way, we can complete the acceleration diagram. And now, what is to be determined? The acceleration of midpoint that is acceleration of D. So, from the measurement, the acceleration of D that will be measurement of vector O dash D dash multiplied by scale. So, measure the length O dash D dash that is from the measurement it is 6.1 centimeter. So, 6.1 into scale 19.3 meter per second square. So, acceleration of D will be 117 point. So, tangential component of AB that can be obtained by measuring the vector x dash x A dash. So, measure the vector x A dash multiplied by scale. So, you will get the tangential component of A with respect to B. So, by the measurement, the vector x A dash is equal to 5.2 centimeter. So, 5.2 into 19.3 meter per second square that is the scale. And hence, the acceleration will be 102.29 meter per second square. And now, references, this material is referred from the book of theory of machines by Avis Khurmi and S.S. Vatan. Thank you.