1. Which of the following is true of the coefficient of static friction? A. It is a number that indicates how difficult two surfaces are to slide past one another. B. It depends on the surface area in contact. C. It is the same for all materials.

21. Cooking an omelet on a boat is tricky because the tilting of the boat can cause the omelet to slip off the flat griddle. If the coefficient of static friction between the omelet and the griddle is 0.05, what is the largest angle (measured from the horizontal) that the griddle can tilt before the omelet starts to slide? A) 3° B) 6° C) 9° D) 12° E) 15°

1. Two blocks are positioned on surfaces, each inclined at the same angle of 42.8 degrees with respect to the horizontal. The blocks are connected by a rope which rests on a frictionless pulley at the top of the inclines as shown, so the blocks can slide together. The mass of the black block is 2.07 kg, and the coefficient of kinetic friction for both blocks and inclines is 0.510. Assume static friction has been overcome and that everything can slide. What is must be the mass of the white block if both blocks are to slide to the LEFT at an acceleration of 1.5 m/s^2? 2. Two blocks are positioned on surfaces, each inclined at the same angle of 49.5 degrees with respect to the horizontal. The blocks are connected by a rope which rests on a frictionless pulley at the top of the inclines as shown, so the blocks can slide together. The mass of the black block is 2.24 kg, and this time there is NO friction. What is must be the mass of the white block if both blocks are to slide to the LEFT at…

5) A box with mass m=1.25 kg rests on the top of a bar. The coefficient of static friction between the box and the bar is μs=0.73 and the coefficient of kinetic friction is μk=0.39. a) Write an expression for Fm the minimum force required to produce movement of the box on the top of the bar.  b) Solve numerically for the magnitude of the force Fm in Newtons. c) Write an expression for a, the box's acceleration, after it begins moving. (Assume the minimum force, Fm, continues to be applied.)  d) Solve numerically for the acceleration, a in m/s².

2. A block of mass 3.00 kg is pushed up against a wall by a force P that makes a 50.0° angle with the horizontal as shown in the figure. The coefficient of static friction between the block and the wall is 0.250. Determine the possible values for the magnitude of P that allow the block to remain stationary 50.0° P

sonia- m pject Pool partment... 7 1 1329 2 S X 7. A 7.50 kg block is pressed against a vertical wall by a force (F), as shown in the figure below. The coefficient of static friction between the block and the wall is 0.41 and the directional angle 8 for the force is 50.0°. Determine the magnitude of the force (F) when the block is about to slide down the wall. N 3 E D 80 F C $ 4 R F % 5 V T G (2991109 911 6 ccito coi16 MacBook Air 6: B S Y H & 7 S 63 91129 911539115 91109 91103 911931 92 U N 6 ceiloo cc 16 ecil6 ceiló ccrl6 cc 16. c 8 J ció ecil6 ceil D-Il ER 1 M ( 9 K MOSISO O O 4 19 P

4. The 100-kg crate is subjected to the forces shown. If it is originally at rest, determine the distance it slides in order to attain a speed of v= 6 m/s. The coefficient of kinetic friction between the crate and the surface is Hk = 0.2. 500 N 400 N 30° 45°