 Hi everyone. I am Mr. Sachin Rathod, Assistant Professor from Mechanical Engineering Department from Walsh Institute of Technology, Swallapur. Today we are going to deal with numericals on velocity and mechanism by using the relative velocity method. The learning outcome of this session is student will be able to calculate the velocity of particular link by relative velocity method. In the last lecture, we have seen what is the basic concept behind the relative velocity method. Today we will solve one numerical on relative velocity method. So, the problem is about the slider crank mechanism. The question is the crank and the connecting rod of the reciprocating engine are 200 mm and 700 mm respectively. The crank is rotated in the clockwise direction at 120 radian per second. Find with the help of relative velocity method first velocity of piston, velocity of midpoint of the connecting rod and angular velocity of the connecting rod. At instant when crank is at 30 degree to the idc. So, first of all, we have to draw the space diagram as per the given dimension. So, first of all, they had given us the slider crank mechanism. Suppose this is a o-point. They had given us the crank makes 30 degree with the idc. Suppose this is your slider, motion of the sliders and the crank makes 30 degree with the idc. So, the position of the crank will come here. It makes the 30 degree. So, by using the set square marks the 30 degree. So, it makes the 30 degree with the idc. And the value is 200 mm. So, by taking some suitable scale, you will take the scale 1 centimeter is equal to 80 mm. So, by taking that scale, we are getting the a-point. Next, this is called as a crank and the 700 mm connecting rod. So, from the a-points by using the compass, you have to mark the 700 mm. So, we have taken a scale as 80. So, 700 divided by 80. We have to take that scale and we have to mark here. We are getting the point b. So, at this is the point b, this is the connecting rod, crank and this is the slider. We will give the name b, name a. And they had given, they had asked to find out the velocity at the midpoint. So, we have to find out the midpoint of this connecting rod. This is your the c-point is nothing but the midpoint. So, actually this one is your the given problem. So, we have drawn as per the given specification. Now, we have to draw the velocity diagram. This diagram is called as a space diagram. This diagram is called as a space diagram. We have to draw the velocity diagram. So, first of all, we have to find out the fixed point. So, here o is nothing but the fixed point. And the velocity of any fixed point, we are getting the velocity is zero. So, here consider any point in the space at that point, the velocity is zero. So, this is the o point at which the velocity is zero. Now, they had given us the crank rotates in clockwise direction. So, this crank is rotated in this direction. So, o point. Now, we have to draw the velocity of crank away. So, it is rotated in the clockwise direction. So, a point is moving perpendicular to the oa. This will use the velocity of a. So, that is why from the o points, we have to draw the line perpendicular to the oaling. So, this is the perpendicular line. So, from the o points, we have to draw the perpendicular to the oaling. We are getting the a point. This is in the direction. And the magnitude is equal to, they had given us the angular velocity of crank. They had given us angular velocity omega oa is equal to 120 radian per second. Therefore, we can easily find out the velocity of oaling. We are knowing v is equal to r into omega. So, velocity of oa is equal to radius of oa. Radius of oa is 0.2 meter into angular velocity 120 radian per second. So, we are getting 24 meter per second. So, by taking some suitable scales, we have to draw the magnitude of oa. So, it will use the velocity of a in the magnitude as well as in the direction. Now, the next one, link a, b is there. So, we are knowing that the velocity of any link is perpendicular to that link. So, we have to draw the perpendicular line. So, from the a points, draw the perpendicular line to the link a, b. And b is the slider. So, the slider always moving in the same direction. So, we have to draw the parallel line to the slider. So, here we are getting the intersecting point b. So, it will use, if we measure this length, it will use the velocity of b. If we measure this length, it will use the velocity of a with respect to b. So, that ask the question, find the velocity of piston. So, for the simplification purpose, here make one table in which link, here we can write down the link oa and link a, b. Here radius in meter. So, the radius of link oa is 0.2 and radius of a, b is 0.7. Here velocity in meter per second. Here already we got the velocity of oa is 24 meter per second. Now, we have to find out the velocity of a, b. So, in this diagram measure this length. So, it is 4.45. So, here we are getting velocity of a, b is equal to 4.45. It is in the centimeter. So, we have taken a scale for this. 1 centimeter is equal to 5 meter per second. So, multiplied by 5, 4.45 into 5, we are getting 22.25 meter per second. So, it will give the velocity of a, b is 22.25. So, they had asked find the velocity of piston. So, velocity of piston is nothing but this is nothing but the o, b. So, measure this length. So, it is a 3 centimeter. So, velocity of piston that is nothing but the b is equal to 3 centimeter into the scale 5. It will give 15 meter per second. So, we are getting the velocity of piston first answer. Second, they had asked the find out the velocity of midpoint of connecting rod. So, c is the midpoint of the connecting rod a, b. Similarly, you can find out the midpoint of the a, b. So, here we are getting the midpoint a, b, c. So, they had asked the find out the midpoint velocity of the midpoint. The velocity of midpoint just we have to find out the velocity of one point. So, we have to calculate the absolute velocity. For finding the absolute velocity, we have to join o to c point. So, this length will give you the velocity of c point. It is near about 3.4. So, velocity of c is equal to 3.4 into the scale 5. We are getting 17 meter per second. So, it will give the velocity of the midpoint. Next one, they had asked angular velocity of connecting rod. So, the a, b is the connecting rod. If you measure this a, b, here we have calculated the velocity 22.25. From this velocity, we have to calculate the angular velocity. We are knowing the relation v is equal to r omega. We have to find out the velocity of a, b, radius of a, b, angular velocity of a, b. So, angular velocity of a, b is equal to 22.25 divided by radius of a, b is 0.7 is equal to 31.78. Radiant per second. So, like this, we have to calculate the velocity as well as angular velocity of each element in the given mechanism. So, I have taken this reference. Thank you.