4. Determine the smallest horizontal for P required to pull out a wedge A. The crate has weight of 300 Ib and the coefficient of static friction at all contacting surfaces is 0.3. Neglect the weight of the wedge. 1S 5. For a systerm shown, determine the maximum weight of the box that will cause the crates to move up. Use coefficient of friction for contact surface, 0.35. 7

4. Determine the smallest horizontal for P required to pull out a wedge A. The crate has weight of 300 Ib and the coefficient of static friction at all contacting surfaces is 0.3. Neglect the weight of the wedge. 1S 5. For a systerm shown, determine the maximum weight of the box that will cause the crates to move up. Use coefficient of friction for contact surface, 0.35. 7

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter7: Dry Friction

Section: Chapter Questions

Problem 7.56P: The square-threaded screw 0f the C-clamp has a mean diameter of 8 mm and a pitch of 1.6 mm. The...

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The square-threaded screw 0f the C-clamp has a mean diameter of 8 mm and a pitch of 1.6 mm. The coefficient of static friction between the threads is 0.2. If the torque C=1.50Nm is used to tighten the clamp, determine (a) the clamping force; and (b) the torque required to loosen the clamp.
The coeffient of static friction between the uniform bar AB of weight W and the ground is 0.45. Find the smallest angle and the corresponding force P that would initiate simultaneous tipping and sliding of the bar.
The screw of the clamp has a square thread of pitch 0.16 in. and a mean diameter of 0.6 in. The coefficient of static friction between the threads is 0.4. Determine (a) the torque C0 that must be applied to the screw in order to produce a 28-lb clamping force at A; and (b) the torque required to loosen the clamp.
The test specimen AB is placed in the grip of a tension-testing machine and secured with a wedge. The coefficient of static friction at both surfaces of the specimen is s. If the wedge angle is =18, determine the smallest s for which the grip is self-locking (no slipping takes place regardless of the magnitude of the force P). Neglect the weight of the wedge.
Determine the smallest coefficient of static friction at A for which the system shown is self-locking (can support the force P of any magnitude). Neglect the weight of bar AB.
Determine the smallest horizontal force P that must be applied to block B to cause impending motion. The angles of static friction are 15 between the blocks and 30 between the blocks and the ground.
A uniform plank is supported by a fixed support at A and a drum at B that rotates clockwise. The coefficients of static and kinetic friction for the two points of contact are as shown. Determine whether the plank moves from the position shown if (a) the plank is placed in position before the drum is set in motion; and (b) the plank is first placed on the support at A and then lowered onto the drum, which is already rotating.
A wedge is used to prop up the 6000-lb block of marble. The wedge angle is =30, and the angle of static friction is s=12 between all contact surfaces. Determine the smallest force P that would prevent the wedge from sliding out.
The brake pads at C and D are pressed against the cylinder by the spring BF. The coefficient of static friction between each pad and the cylinder is 0.15. Find the smallest tension in the spring that would prevent the cylinder from rotating when the clockwise couple M=2200lbin. is applied. Neglect the weights of the members.
The mass of the unbalanced disk is m, and its center of gravity is located at G. If the coefficient of static friction is 0.2 between the cylinder and the inclined surface, determine whether the cylinder can be at rest in the position shown. Note that the string AB is parallel to the incline.
The square-threaded screw with a pitch of 10 mm and a mean radius of 18 mm drives a gear that has a mean radius of 75 mm. The static and kinetic coefficients of friction between the gear and the screw are 0.12 and 0.06, respectively. The input torque applied to the screw is C0=10Nm. Assuming constant speed operation, determine the output torque C1 acting on the gear.
The screw of the carjack has a pitch of 0.1 in. and a mean radius of 0.175 in. Note that the ends of the screw are threaded in opposite directions (right- and left-handed threads). The coefficient of static friction between the threads is 0.08. Calculate the torque C0 that must be applied to the screw in order to start the 1200-1b load moving (a) upward; and (b) downward.