Michael Jordan has a portable basketball hoop in his driveway. He has set the basket at 8 ft (2.4 m) high so he can practice dunking the ball (he’s a bit older now, so he can’t quite jump “Air” Jordan style).  He slams the ball through the hoop and then hangs on to the rim.  This exerts a downward force of 600 N on the front of the rim.  The front of the rim is 1.1 m in front of the front edge of the portable hoop’s base.  The mass of the whole portable basketball hoop is 70 kg.  The center of gravity of the portable hoop is 1.0 m behind the front edge of the base. How much torque is produced around the front of the hoop base by the 600 N force Air Jordan exerts on the front of the rim? How much torque is needed to tip the hoop? What is the largest vertical force that can be exerted on the front edge of the rim before the portable hoop begins to tip?

Homework Q4.

Understanding the details of timing and forces in motion can improve the performance of athletes, including dancers. Consider the forces involved in a ballet jump called a sauté demi plié. P9.84a shows the sequence of moves in the jump. The dancer starts upright, then quickly bends her knees, moving downward. After she reaches the bottom of this dip, she extends her legs, pushing herself upward. After this upward push, she leaves the ground, beginning a short period of time in the air. P9.84b is a slightly idealized graph of the net force on a 42 kg dancer executing this move. At what time does the dancer reach the lowest point of her motion, when her speed is zero?A. 0.20 sB. 0.40 sC. Between 0.40 s and 0.70 sD. After 0.70 s

An Atwood’s machine consistsof blocks of masses m1 =10.0 kgand m2 = 20.0 kg attached by a cordrunning over a pulley as in FigureP8.46. The pulley is a solid cylinderwith mass M = 8.00 kg and radiusr = 0.200 m. The block of mass m2 isallowed to drop, and the cord turnsthe pulley without slipping. (a) Whymust the tension T2 be greater thanthe tension T1? (b) What is the accelerationof the system, assuming thepulley axis is frictionless? (c) Find thetensions T1 and T2.

A turntable with a mass of 12 kg and a radius of 2 meters spins at a constant angular velocity of 140 rpm. A 500-gram scoop of uniformly-dense ice cream falls onto the turntable, so the scoop's center of mass is one meter away from the turntable's center. The scoop forms a hemisphere and has a radius of 4 cm. If there's no friction between the brick and ice cream scoop and they spin at the same angular speed, what is their final angular speed, in rev/min or in rad/s? Justify your answer with your rationale and equations used. Moments of Inertia: Idisk =MR for rotation about its center of mass parallel to the z-axis. %3D Ihemisphere = MR for rotation about its center of mass parallel to the z-axis. Edit View Ansert Format Tools Table COREI

Figure P8.74 shows a vertical force applied tangentially to a uniform cylinder of weight w. The coefficient of static friction between the cylinder and all surfaces is 0.380. Find, in terms of w, the maximum force F that can be applied without causing the cylinder to rotate. (Hint: When the cylinder is on the verge of slipping, both friction forces are at their maximum values.) Figure P8.74

A student stands on a platform that is free to rotate and holds two dumbbells, each at a distance of 65 cm from his central axis. Another student gives him a push and starts the system of student, dumbbells, and platform rotating at 0.50 rev/s. The student on the platform then pulls the dumbbells in close to his chest so that they are each 22 cm from his central axis. Each dumbbell has a mass of 1.00 kg and the rotational inertia of the student, platform, and dumbbells is initially 2.40 kg-m². Model each arm as a uniform rod of mass 3.00 kg with one end at the central axis; the length of the arm is initially 65 cm and then is reduced to 22 cm. What is his new rate of rotation? HH 65 cm 65 cm M 22 cm

Three children are riding on the edge of a merry-go-round that is 162 kg, has a 1.60 m radius, and is spinning at 21.3 rpm. The children have masses of 17.4, 28.5, and 38.8 kg. If the child who has a mass of 38.8 kg moves to the center of the merry-go-round, what is the new angular velocity in rpm?

In the figure below, both the ceiling and the ruler accelerate together at 1.6 m/s2 in the +y direction, and the reading to the "new" length of the vertical wire is as indicated. Ignore the effect on the two diagonal wires. Other parameters are below: Weight of the pan = 5 N Weights (or loads) = 74 N Originally, the wire has a length 0.200 cm, and diameter of 2.7 cm. Calculate the Young's modulus of the wire in Pa. NOTES: Use pi = 3.14. Final answer in ZERO decimal place. 4.000 4.100 4.200 4.300 cm

Due to an unequal distribution of fuel in the wing tanks, the centers of gravity for the airplane fuselage A and wings B and C are located as shown. If these components have weights WA = 45 000 lb, Wg = 8000 lb, and Wc = 6000 lb, determine the normal reactions of the wheels D, E, and F on the ground. Bo 8 ft 4 ft 6 ft 8 ft 6 ft 20 ft 3 ft