Department of Mechanical Engineering, MITS-FETApplied Mechanics (ME-201) Tutorial.

Engineering Mechanics (ME 201)TUTORIAL SHEET-7

1. Determine whether the block shown is in equilibrium, and find the magnitude and direction of the friction force when θ = 300 and P = 200N.

ANSWER: Feq. > Fmax impossible ⇒ Block

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F = 193.2 N

2. A 120-mm-radius pulley of mass 5 kg is attached to a 30-mm-radius shaft which fits loosely in a fixed bearing. It is observed that the pulley will just start rotating if a 0.5-kg mass is added to block A. Determine the coefficient of static friction between the shaft and the bearing.ANSWER:

μs = 0.0787

3. The block and tackles shown are used to raise a 600-N load. Each of the 60-mm-diameter pulleys rotates on a 10-mm-diameter axle. Knowing that the coefficient of kinetic friction is 0.20, determine the tension in each portion of the rope as the load is slowly raised.

ANSWERTAB = 290 N, TCD = 310 N, TEF = 331N

4. Determine the distance s to which the 90 kg painter can climb without causing the 4 m ladder to slip at its lower end A. The top of 15 kg ladder has a small roller, and at the ground the coefficient of static friction is 0.25. The mass centre of the painter is directly above his feet.

ANSWERS = 2.55 m

5. The collar A has a force fit on shaft B and is to be removed from the shaft by the wheel-puller mechanism shown. The screw has a single thread with a mean diameter of 20 mm and a lead L of 6 mm. If a torque of 24 N-m is required to turn wheel C to slip the collar off the shaft, determine the average pressure p (compressive stress) between the collar and the shaft. The coefficient of friction for the screw at E is 0.25, and that for the shaft and collar is 0.30. Friction at the ball end D of the shaft is negligible.ANSWERp = 2400 kPa.

6. The horizontal position of the 500-kg