4 questions to be answered

7. || The radius of the earth's very nearly circular orbit around the sun is 1.50 x 10" m. Find the magnitude of the earth's (a) velocity and (b) centripetal acceleration as it travels around the sun. Assume a year of 365 days. 20. | A wind turbine has 12,000 kg blades that are 38 m long. The blades spin at 22 rpm. If we model a blade as a point mass at the midpoint of the blade, what is the inward force necessary to provide each blade's centripetal acceleration? 60. | | BIO Biologists have studied the running ability of the northern quoll, a marsupial indigenous to Australia. In one set of experiments, they studied the maximum speed that quolls could run around a curved path without slipping. One quoll was running at 2.8 m/s around a curve with a radius of 1.2 m when it started to slip. What was the coefficient of static friction between the quoll's feet and the ground in this trial? 67. III INT The 0.20 kg puck on the frictionless, horizontal table in Figure P6.67 is connected by a string through a hole in the table to a hanging 1.20 kg block. With what speed must the puck rotate in a circle of radius 0.50 m if the block is to remain hanging at rest? Figure P6.67 0.20 kg r= 0.50 m 1.20 kg