Problem 4: To get it spinning, you exert a force of 180 N perpendicular to the radius of a 0.28 m radius grindstone (a solid disk) of mass 75 kg. a) What is the magnitude of the torque exerted? b) What is the angular acceleration assuming negligible friction in the grindstone's axel?

A discus thrower moves the discus in 2.30 complete revolutions about his body in 1.32 s (starting from rest). The radius of the circular path of the discus is 0.900 m, and the mass of the discus is 2.00 kg. Assume that a constant torque is applied to the discus by the athlete. A) What is the angular speed of the discus just before release? in rad/s B) What torque does the athlete apply to move the discus about his body? in N*m C) Approximately how far from the athlete does the discus land if it is released at a 45.0° angle to the horizontal until it returns to the same height as it was released? in m

Suppose you exert a force of 195 N tangential to the outer edge of a 1.41-m radius 77.5-kg grindstone (which is a solid disk). 1) What is the torque τ, in newton meters, you are exerting on the grindstone, relative to the center of mass of the grindstone? τ = 2) What is the angular acceleration of the grindstone α0, in radians per square second, assuming negligible friction? α0 = 3) What is the angular acceleration of the grindstone αf, in radians per square second, if there is an opposing frictional force of 20.5 N exerted 0.35 m from the axis? αf =

A playground merry-go-round has a mass of 100 kg and a radius of 1.80 m and it is rotating with an angular velocity of 0.500 rev/s. What is its angular velocity after a 22.0-kg child gets onto it by grabbing its outer edge? The child is initially at rest.

A student holds a bike wheel and starts it spinning with an initial angular speed of 9.0 rotations per second. The wheel is subject to some friction, so it gradually slows down. In the 10.0 s period following the inital spin, the bike wheel undergoes 77.5 complete rotations. Assuming the frictional torque remains constant, how much more time At, will it take the bike wheel to come to a complete stop? Ats = S The bike wheel has a mass of 0.825 kg and a radius of 0.315 m. If all the mass of the wheel is assumed to be located on the rim, find the magnitude of the frictional torque 7† that was acting on the spinning wheel. N- m

Suppose a yo-yo has a center shaft that has a 0.290 cm radius and that its string is being pulled. (a) If the string is stationary and the yo-yo accelerates away from it at a rate of 1.70 m/s?, what is the angular acceleration of the yo-yo in rad/s?? |rad/s² (b) What is the angular velocity in rad/s after 0.750 s if it starts from rest? rad/s (c) The outside radius of the yo-yo is 3.60 cm. What is the tangential acceleration in m/s? of a point on its edge? |m/s²

A meterstick of negligible mass is pivoted at the 0.60 m mark with a 2.0 kg blue bag on one end and a 1.0 kg red bag on the other, at the 1.0 m mark. The stick is released from rest in a horizontal position. Find the magnitude of the net torque on the meterstick about the pivot point. Pick the value on the nearest whole number. O 10 N.m 16 N.m 8.0 N.m ○ 2.0 N.m

The graph below is for a 30 kg.m2 object. a) Find the net torque. b) Find the angular displacement at t = 3.5 s

a top with radius 10cm, mass 2 kg has a string around the edge and is initially at rest. assume the top can be reasonably approximated as a solid cylinder. the top is held in place as the string is pulled. the string applies a force of 10N tangential to the edge for 2s. what is the angular velocity (in radians per second) of the top after 3 seconds? what is the angular momentum of the top after the string is pulled? after the string is pulled, the top is released. it travels away from its initial position at a linear velocity of 10m/s. what is the rotational velocity (in radians per s) at this top? assume no friction

The platform shown in the figure below (The Merry-Go-Round) has a mass of M- 100 kg and radius R 2.0 m. Lia (m 30 kg) walks slowly from the rim of the disk toward its center. If the angular speed of the system is 2.0 rad/s when Lia is at the rim, what is the angular speed when she reaches a pointr 3- 0.5 m from the center? M