Problem No. 1 A 270 lb block is in contact with a plane inclined at 30 deg to the horizontal. A force P, acting horizontally as shown is applied to the body. If the coefficient of static friction is 0.2: a) find the value of P to just cause motion to impend up the plane; b) find P to just prevent motion down the plane; c) If P = 110 lb, determine the magnitude and direction of the frictional force. %3D Draw the free body diagrams. 300 30°

Problem No. 1 A 270 lb block is in contact with a plane inclined at 30 deg to the horizontal. A force P, acting horizontally as shown is applied to the body. If the coefficient of static friction is 0.2: a) find the value of P to just cause motion to impend up the plane; b) find P to just prevent motion down the plane; c) If P = 110 lb, determine the magnitude and direction of the frictional force. %3D Draw the free body diagrams. 300 30°

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 7.63P: The leather rein used to fasten the horse to the hitching rail weighs 3.5 oz per foot. The...

See similar textbooks

Similar questions

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.
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 leather rein used to fasten the horse to the hitching rail weighs 3.5 oz per foot. The coefficient of static friction between the rail and the rein is 0.6. If a 34-lb force acting on the bridle is sufficient to restrain the horse, determine the smallest safe length L for the free end of the rein.
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.
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.
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.
Calculate the horizontal force P required to push the 85-lb lawn mower at constant speed. The center of gravity of the mower is at G, and the coefficients of rolling resistance are 0.12 for the front wheels and 0.18 for the rear wheels.
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.
Draw the FBD of the entire frame, assuming that friction and the weights of the members are negligible. How many unknowns appear on this FBD?
If PCD=6000lb and PGD=1000lb (both compression), find P and Q.
The figure shows a steel bar being processed by a rolling mill. Given that P=80kN and r =0.016, determine the force F required to advance the bar at a constant speed.
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.