Graphical Method to Calculate Velocity and Acceleration of Four Bar Chain Problem 1


Do subscribe to Ekeeda Channel and Press bell icon to get updates about latest engineering HSC and IIT JEE main and advanced videos Hello students good morning everyone so today we are going to see how 4 Bar chain works and we are going to find the velocity and acceleration of different lengths of 4 parts train so here’s the question first question we have for watch in ABCD AB is fixed and it is 150 mm long the crank AB is 40 mm long and rotates at 120 rpm clockwise while the link CD is 80 mm long and oscillates about point D BC & AD are of equal length find the angular velocity of link CD when the angle BD is 60 degree so this is the question we have to find the angular velocity of link CD so first of all have to draw the configuration diagram that is the first of all you have to draw 4 Bar chain a particular scale after you draw the configuration diagram then you have to go to the velocity diagram and after drawing the velocity diagram you can easily calculate the angular velocity of the link CD if there is a question will it do acceleration that is angular acceleration then you have to also draw the acceleration diagram so if the question is stay talking about only angular velocities of different lengths you have to draw only the velocity diagram if it is talking about angular acceleration of different links you have to draw the acceleration diagram is will so your in this question there is only angular velocity of the link CD so we can get the angular velocity of links you need just by drawing the configuration diagram and the velocity diagram so let’s start with the question let’s start drawing the diagrams before you start towing the configuration diagram you have to check what are the lengths given so according to the length of different links you have to decide a scale so if you check in the question the lengths of different links are 150 mm 40 mm then 80 in them so looking at the values you can select a particular scale so it depends on what or how much I lost diagram that you want if you want a smaller size diagram you can select a bigger scale if you want or a diagram which is very big so you can select a scheme which is very small so you know in this case we can take the scale as values are 80 40 150 so you can take scale as 20 mm is equal to one centimeter scale is 20 mm equal to one centimeter and you have to start doing the configuration diagram the link ad is fixed lane which is generally at the bottom the fixed link is always at the bottom and the link is 150 mm long so 150 divided by 40 150 divided by 20 gives you 7.5 so I’ve drawn the link ADT next is the angle B ad which is given as 60 so next you can plot the angle now in the question if you see the crank is given as 40 mm so I’ve selected a scale as 20mm is one centimeter so the cramp grant will be which is 40 M long which comes out to two centimeter now we’ve got the point B now we have got the point B ba D next is the connecting rhodium from the fixed link we have drawn the link R and that is a B now as a third it’s a faux pas chain so then before links we’ve already done with toolings now is the link BC if you read the question BC an area of equal length so it is 7.5 so BC is also 7.5 now in the question it is given that CD is 80 mm so le tienen comes out to force anything in so we’ve drawn the configuration diagram taking scale as 20m people to one centimeter ABCD is the four-part chain and the link is fixed now we can move on to calculation of the velocity diagram before going to draw before you draw the velocity diagram you have to see the direction in which crank is rotating if you see the question the crank is rotating clockwise in that tube is 120 rpm so you have to show the direction so it is rotating clockwise with 120 rpm so if the item is given to you can even calculate the value of angular velocity Omega of the crank that is 2 pi n by 60 and you can also calculate the velocity of point B with respect to point a also the point B the velocity of point B with respect to it will be perpendicular to the link that is perpendicular to the crank that is the length a B so it will be perpendicular to below total the crank and it will be in the direction in which the crack is rotating so Tron the velocity of B with respect to a it will be having this direction now we can find the magnitude of the velocity of B with respect to a so B is equal to I times Omega Omega so velocity of B with respect to a will be a B in to Omega of a B but the value of Omega a B is not given to you Omega a B can be calculated using the formula 2 pi n by 16 so the value of Omega comes out to twelve point five six radians per second we have to calculate the velocity of B with respect to a which is nothing but R times Omega but the value of Omega is not given to you so you can calculate Omega using two pi n by sixty so the value of Omega comes out to twelve point five six now you can substitute the value of Omega in the equation and get the value of velocity so the value of velocity of V with respect to a comes out to 0.5 0 meters per second now they’ve got the magnitude of velocity we also know the direction of velocity now you can draw the vector the vector V with V velocity of B with respect to a can be drawn because we know that value as well as the direction so when you draw the velocity diagram you have to select a scale before selecting a scale you have to take a point and anywhere how in the page and you have to name the point as a comedy key because the link it is fixed since link it is fixed both the points A and D will be stationary they are not moving although other two points that is B and C as you can see in their diagrams they will be moving and a and D will be fixed point so you have to take a point in the velocity diagram and name them as a commodity now you can go on to calculation of the velocity of B with respect to a we have already calculated the velocity of B with respect to a and the value of that comes out to twelve point five six that is omega I’m sorry velocity of B with respect to a comes out to zero point five zero we also know the direction of velocity of B with respect to a now you can plot the vector selecting a suitable scale so select the scale for velocity diagram so since the value of velocity is point five so let’s take us take the scale as 0.5 0.1 m/s is one centimeter so the value of velocity of B with respect to a will be 5 centimeter since it is 0.5 so we’ve drawn the vector velocity of B with respect to a now we are done with the point B now let’s move to the point C since Point C is connected to two different points as you can see C is connected to B as well as D so there will be two velocities of c.width receive velocity of C with respect to B and velocity of C with respect to D so velocity of C with respect to B will be a vector perpendicular to C B and velocity of C with respect to D will be a vector perpendicular to C D so first let’s draw both the perpendicular lines so on the two vectors that is velocity of C with respect to B which is perpendicular to BC velocity of C with respect to D which is perpendicular to C B now we only know the directions we don’t know the magnitude because if you want to calculate the magnitude of velocity of C with respect to B you should know the angular velocity of the linked CD which is not known if you want to calculate the magnitude of velocity of C with respect to D you should know the angular velocity of the linked CD which is again not known so what we can do is we can just plot there we can just drag the lines in the velocity diagram and we can get the magnitude has been so the velocity diagram is done as you can see we’ve got the triangle so earlier the magnitude was not known the magnitude of the velocity C with respect to D and the magnitude of velocity C with respect to B was not known now as the better diagram is complete you can see there in suffix and now we can get the the value of their velocities that is velocity of C with respect B can be easily found velocity of C with respect to V can also be easily found now let’s go on to the calculation part and calculate the angular velocity of link CD if you were to calculate the value of CD you should know this length VC B and you have to multiply it by scale so first of all let’s measure this length now issue D is known to you now since velocity of C with respect to D is known we can calculate the angular velocity of C with respect to B though CD has to be taken in 10 meters because velocity of C with respect to D is in meters per second so the Lynne Cheney has should also be in meters per second I mean it should also be in meters so the value of CD is given as 80 mm so 80 divided by thousand is 0.08 so Thalia of Omega facility comes out to 0.5 radians per second so this is the configuration diagram this is the velocity diagram the velocity of C with respect to D is only known in direction the velocity of C with respect to D is also only rotary direction the velocity of B with respect to a is known in direction as well as magnitude so you can plot the line rest of the vectors that is V CD and VC B can be already known direction so we can just drag these lines and we can take the triangle once you know the triangle you can calculate the velocity of any of the part once you get the velocity next is you should go on to calculate the angular velocity of whichever link is the whichever link is asked about so once you get the velocity once you get the omega think the question is done so if it is only about angular velocity if it is also regular acceleration you have to continue with that angular acceleration diagram as well so I hope you understood this thank you so much

67 thoughts on “Graphical Method to Calculate Velocity and Acceleration of Four Bar Chain Problem 1

  1. Thank you so much sir for such useful videos….but why are you not uploading all the videos…some videos are private… please share them also

  2. Man but there is a some error while you are dragging your protractor(scale) parallel to vcd and vcb velocity vectors.If there is a certain dismantle in positioning those vector in velocity diagram the answer would change accordingly

  3. Please upload acceleration diagram next month I have exams please help me sir thank you.

  4. man ı am engıneer and thank Indıan teachers everythıng avalıable on the youtube. But now ı speak lıke them, Thank you very much, sir, for sharıng your knowledge wıth us.

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  6. Bro you are very great….. Thnxxx yaar… Your language is very easy… I understand very easy… Thmxxx bro…

  7. "Graphical Method to Calculate Velocity and Acceleration of Four Bar Chain Problem 1" No acceleration included… You're an idiot.

  8. what i didnot understand is how b and c were given point name in velocity diagram? I however understood it with critical thinking but not conceptually

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