HW#17 Ch 6: Force and Motion — II
Instructions: Show all work using Newton’s 2nd law and free body diagrams.
1. One end of a 70 cm string is tied around a vertical pole on a horizontal table, and the other end is attached to the side of a motorized toy car of mass 352 grams. The car starts from rest, and accelerates at a constant rate of 0.8 m/s2 (in the tangential direction) while moving in a horizontal circle around the pole. If the tension in the string is rated at 2.2 N just before breaking, a) how fast is the car moving when the string breaks? b) How long does it take for the string to break? c) What is the magnitude of the car’s acceleration just as the string breaks (don’t forget that there is radial acceleration as well).
2. The Texas Skyscreamer is the tallest swing-ride in the world at 400 ft, featuring a rigid upper platform of radius 23.42 m, and seats suspended from 26.77 m chains (see accompanying figure). As the platform rotates, the seats swing outward, making a maximum angle of 33° with the vertical. a) What is the maximum tangential speed of the seat? b) What g-force does a rider experience? Express as a multiple of g, with the constant appearing as a decimal. (To calculate the g-force acceleration, simply divide the normal force by the mass.)
3. You are driving a Cadillac around a horizontal circle of radius 190 m, at a speed of 99 km/h in inclement weather, when the tires start to slip. What is the coefficient of static friction between the tires and the road?
4. A large spherical raindrop of density ρ = 1000 kg/m3 and radius 2.5 mm reaches a maximum terminal velocity of 9 m/s. If the drag force is in the form of FD = bv2, what is the value of b, including units?