Sisyphus was a character in Greek mythology and was doomed in Hades to push a boulder to the top of a steep mountain.  When he reached the top, the boulder would roll back down the mountain and he would have to start all over again.  The coefficient of static friction between the boulder and the mountainside is 0.200, the mass of the boulder is 136kg (300 lbs), and the slope of the mountain is a constant 30.00.  What is the force in pounds that Sisyphus must exert on the boulder to move it up the mountain at a constant velocity?

In the figure, a rectangular slab of slate rests on a bedrock surface inclined at angle 0 = 27.8°. The slab has length L = 41.2 m, thickness T = 7.51 m, and width W = 14.1 m, and 1.0 cm³ of it has a mass of 3.2 g. The coefficient of static friction between slab and bedrock is 0.315. (a) Calculate the component of the gravitational force on the slab parallel to the bedrock surface. (b) Calculate the magnitude of the static frictional force on the slab. By comparing (a) and (b), you can see that the slab is in danger of sliding. This is prevented only by chance protrusions of bedrock. (c) To stabilize the slab, bolts are to be driven perpendicular to the bedrock surface (two bolts are shown). If each bolt has a cross-sectional area of 7.06 cm² and will snap under a shearing stress of 3.06 × 108 N/m², what is the minimum number of bolts needed? Assume that the bolts do not affect the normal force. (a) Number i (b) Number (c) Number i Units Units Units <

A block weighing mA = 10 kg is placed on a plane with slope angle 30.0 degrees and is connected to a hanging weight of mass mB by a cord passing over a small frictionless pulley as shown in the picture. The coefficient of static friction is 0.42, and the coefficient of kinetic friction is 0.30. If the two blocks are moving, what is the force of friction?

A block with a mass of 9.32 kg is placed on a ramp. The ramp has an incline of ? = 20.2 degrees from the horizontal. The static coefficient of friction between the block and ramp is μs = 0.255, and the kinetic coefficient of friction between the block and ramp is μk = 0.134. A force, F, is exerted on the block as shown. Note that the force F is parallel with the ramp. What is the smallest value (magnitude) for the force, F, in Newtons that can be exerted on the block to hold the block stationary on the ramp?  What is the largest value (magnitude) for the force, F, in Newtons that can be exerted on the block while still holding the block stationary on the ramp?  What value (magnitude) for the force, F, is needed to move the block up the ramp at a constant speed?

An empty pail and a 34 kg wooden mass are tied together by a very light string which passes over a massless and frictionless pulley. There is a force of friction between the mass and the table and there is a coefficient of static friction of 0.76 and a coefficient of kinetic friction of 0.46. Water is added to the bucket one drop at a time until the system just begins to move. When the system just begins to move, what will the acceleration be? (Answer to 1 decimal place, use g = 9.8m/s2)

(a) A flatbed truck moving at 28 m/s carries a steel girder that rests on its wooden floor. The girder is not strapped down, in violation with USDOT regulations. If the coefficient of static friction between steel and wood is 0.52, what is the minimum distance over which the truck can come to a stop without the girder sliding toward the cab of the truck? (answer: 77 m) (b) What is the minimum time over which the truck can accelerate forward from 0 m/s to 28 m/s with a constant acceleration without the girder sliding off the back? (answer: 5.5 s) FNET = ma fs.max = μsn W = mg v² = v₁² + 2aAx V = Vo+ at g=9.81 m/s²

A block with a mass of 6.18kg slides down a ramp inclined at 30.0o.  The coefficient of kinetic friction between block and ramp is uk=0.490. The kinetic friction force acting on the block as it slides has a magnitude of ________N.

Problem 6. A 6.0kg block is placed on top of a 9.0kg block. A horizontal force of 50.0N is applied at an angle to the 9.0kg block, and the 6.0kg block is tied to the wall by a rope. The coefficient of kinetic friction between the two blocks is 0.25, and the coefficient of friction between the 9.0kg block and the ground surface is 0.30. (a) Draw a free body diagram for each block and identify the action-reaction forces between the blocks. (b) Determine the tension in the rope. (c) Determine the magnitude of the acceleration of each block. 6.0kg F = 50.0N 15° 9.0kg

A heavy sled is being pulled by two people, as shown in the figure. The coefficient of static friction between the sled and the ground is µs = 0.603, and the kinetic friction coefficient is = 0.403. The combined mass of the sled and its load is m = 336 kg. The ropes are separated by an angle o = 25.0°, and they make an angle 0 = 31.1° with the horizontal. Assuming both ropes pull equally hard, what is the minimum rope tension required to get the sled moving? minimum rope tension: N If this rope tension is maintained after the sled starts moving, what is the sled's acceleration? acceleration: m/s2

You are using a modified block and tackle pulley system to lift a concrete block. You need to lift the concrete block (mass=200kg) a distance of 5 meters upward. The system is designed to reduce the force loaded by a factor of 4. How much rope must you pull down on the other side of the pulley to lift the block the proper distance?