Download GTU B.Tech 2020 Summer 3rd Sem 3131906 Kinematics And Theory Of Machine Question Paper

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Subject Code: 3131906

GUJARAT TECHNOLOGICAL UNIVERSITY

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BE - SEMESTER- III EXAMINATION - SUMMER 2020

Subject Name: Kinematics and Theory of Machine

Time: 02:30 PM TO 05:00 PM

Date: 04/11/2020

Total Marks: 70

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Instructions:

1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q1

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1. Define the following terms: (1) Module of gear (2) Pressure angle in cam-profile (3) Self-locking brake. [MARKS 03]
2. Define the following terms (1) Lower pair (2) Higher pair (3) successfully constrained motion (4) completely constrained motion [MARKS 04]
3. Explain the working principle of any quick return mechanism with a neat sketch. [MARKS 07]

Q2

1. Explain the relation between linear and angular terms: displacement, velocity and acceleration [MARKS 03]

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2. In a crank and slotted lever quick return mechanism, the distance between the fixed centers is 300 mm and the length of the driving crank is 150 mm. Determine the ratio of the time taken on the cutting and return strokes [MARKS 04]
3. The crank of a slider crank mechanism rotates clockwise at a constant speed of 10 rad/s. The crank OA is 150-mm and connecting rod AB is 600 mm long. Determine the acceleration of connecting rod AB, acceleration of slider B. When crank is at 45° from the inner dead center position. [MARKS 07]

OR

1. A four-bar mechanism ABCD, the length of the various links is given as AB =190 mm, BC = CD =280 mm, AD = 500 mm. ?BAD = 55°. The crank rotates at 10 rad/s in the clockwise direction. Determine... (a) the acceleration of link BC and CD and (b) the angular acceleration of link BC and CD. [MARKS 03]
2. Explain Rigid link, Flexible link and Fluid link with example. [MARKS 04]

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3. State and prove ‘Aronhold Kennedy’s Theorem’ of three instantaneous centers. [MARKS 07]

Q3

1. Define rubbing velocity at a pin joint. What will be the rubbing velocity at a pin joint when the two links move in the same and opposite directions? [MARKS 03]
2. Explain in brief Function, Path & Motion Generation [MARKS 04]
3. Synthesize a four-bar mechanism to meet the following instantaneous conditions for input output links: ?2 =60°, ?4 =90°, ?2 = 3 rad/sec, ?4 = 2 rad/sec, a2 = -1 rad/sec², a4 =0 [MARKS 07]

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Q.3

1. Design a four-bar chain mechanism, governed by the function y= 2x² for the range 2 < x < 4 Assuming ? vary between 40° and 120° for the input link and f vary between 60° and 132° for the output link. Find the value of x , y , ? and f corresponding to three precision point. [MARKS 03]
2. What do you understand by the term “interference” as applied to the gear? [MARKS 04]
3. Bridges and roof of workshop uses structure element, justify with reason. [MARKS 07]

Q4

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1. Draw the cam profile operating knife edge follower from following data (1) Follower to move out through distance of 40mm during 100° (i1) Follower to dwell for next 80°. (ii1) Follower to return to its initial position during 90°. (iv) Follower to dwell for remaining cam rotation [MARKS 03]
2. The cam shaft rotates at 900rpm. The minimum radius of cam is 50mm and line of follower is offset 15mm from the axis of the cam and displacement to take place with uniform acceleration and retardation for both inward and outward stroke. [MARKS 04]

OR

1. Define the following terms: (1) Dry friction (2) Film friction (3) Limiting angle of friction [MARKS 03]
2. Find maximum velocity and acceleration for‘outward and return stroke for the data given in above problem 4(c) and draw the displacement, velocity and acceleration diagram. [MARKS 04]

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3. Explain with sketches the different types of cams and followers [MARKS 07]

Q5

1. Show that velocity ratio for compound belt drive is given by N1/N4 = (d2 * d4) / (d1 * d3) [MARKS 03]
2. Derive an expression for the length of path of contact for two involute profile gear in mesh. [MARKS 04]
3. The pressure angle of two gear in mesh is 20° and have a module of 10mm. The number of teeth on pinion are 24 and on gear 60. The addendum of pinion and gear is same and equals to one module. Determine ... (a) the number of pairs of teeth in contact (b) the angle of action of the pinion and gear. [MARKS 07]

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OR

1. Explain the phenomena of slip and creep in a belt drive. [MARKS 03]
2. Explain with the neat sketch the “sun and planet wheel”. [MARKS 04]
3. Find the power transmitted by a belt running over a pulley of 600mm diameter at a speed of 200 rpm. The coefficient of friction between belt and the pulley is 0.25, angle of lap 160° and maximum tension in the belt is 2500 N. [MARKS 07]

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