angle of friction

Problem 544
The block A in Fig. P-544 supports a load W and is to be raised by forcing the wedge B under it. If the angle of friction is 10° at all surfaces in contact, determine the maximum wedge angle α that will give the wedge a mechanical advantage; i.e., make P less than the weight W of the block.
 

Problem 543
To adjust the vertical position of a column supporting 200-kN load, two 5° wedges are used as shown in Fig. P-543. Determine the force P necessary to start the wedges is the angle of friction at all contact surfaces is 25°. Neglect friction at the rollers.
 

Problem 542
What force P must be applied to the wedges shown in Fig. P-542 to start them under the block? The angle of friction for all contact surfaces is 10°.
 

Problem 541
Determine the force P required to start the wedge shown in Fig. P-541. The angle of friction for all surfaces in contact is 15°.
 

Problem 540
As shown in Fig. P-540, two blocks each weighing 20 kN and resting on a horizontal surface, are to be pushed apart by a 30° wedge. The angle of friction is 15° for all contact surfaces. What value of P is required to start movement of the blocks? How would this answer be changed if the weight of one of the blocks were increased by 30 kN?
 

Problem 539
The block A in Fig. P-539 supports a load W = 100 kN and is to be raised by forcing the wedge B under it. The angle of friction for all surfaces in contact is f = 15°. If the wedge had a weight of 40 kN, what value of P would be required (a) to start the wedge under the block and (b) to pull the wedge out from under the block?
 

Problem 538
In Problem 537, determine the value of P acting to the left that is required to pull the wedge out from under the 40-kN block.
 

Problem 537
In Fig. P-537, determine the value of P just sufficient to start the 10° wedge under the 40-kN block. The angle of friction is 20° for all contact surfaces.
 

Problem 536
in Fig. P-536, determine the minimum weight of block B that will keep it at rest while a force P starts blocks A up the incline surface of B. The weight of A is 100 lb and the angle of friction for all surfaces in contact is 15°.
 

Problem 535
A wedge is used to split logs. If φ is the angle of friction between the wedge and the log, determine the maximum angle a of the wedge so that it will remain embedded in the log.