PHYS-161 Test 2 Review 1 1. A ride in an amusement park consist of a cylinder of radius 3 rotating at an angular speed of 5 /. The floor drops away leaving the riders suspended against the wall as shown. What minimum coefficient of friction between the rider and the wall will keep the rider from slipping? Answer: 0.131 2. YF.5.110 (modified). A 3 ball is connected to a rotating rod by two massless strings, each of length = 5 . The strings are tied to the rod with a separation = 6 and are taut. The tension in the upper string is 100 . The ball rotates in a horizontal circle at a constant tangential speed. Use = 10

2 . a. Draw the free-body diagram (FBD) for the ball. b. Choose a coordinate system and show the components of the forces. What is the direction of the net force on the ball? c. Find the tension in the lower string. d. Find the magnitude of the net force on the ball. e. Find the speed of the ball. Answer: 50 , 120 , 410 /

3. A block slides along a path without friction until it reaches the section of length = 0.75 , which is at height = 2 on a ramp of angle = 30. In that section the coefficient of kinetic friction is = 0.4. The block passes though point with a speed of 8 /. If the block can reach point , where the friction ends, what is its speed there, and if it cannot, what is its greatest height above ? Answer: 3.5 /

4. Two blocks of masses = 2 and 2 are connected to a spring of constant = 200 / that has one end fixed. The horizontal surface and the pulley are frictionless and pulley has negligible mass. The blocks are released from rest with the spring relaxed. a. What is the combined kinetic energy of the two blocks when the hanging block has fallen 0.09 ? b. What is the kinetic energy of the hanging block when it has fallen 0.09 ? c. What maximum distance does the hanging block fall before momentarily stopping?