You are trying to get a better feel for the effect of geometry and mass distribution on the moment of inertia. You have a solid disk and a thin ring, each of radius, r = 1.30 m, and mass, m = 73.0 kg. You mount both on fixed, horizontal frictionless axes about which they can spin freely. Then you spin them both. (a) How much work do you need to do to get each object to spin at 3.00 rad/s? (b) Let us assume that you have been causing them to spin by using a constant force applied tangentially to their circumferences. If the above speed is to be reached within 0.700 s, what is the magnitude of the force you need to apply to each object? (c) You next attempt to stop each object by pressing one finger on each side of each object, right at the outer edge. The coefficient of kinetic friction between each finger and the surface of each object is 0.300. Find the minimum force you have to apply to stop each object within 1.00 min.

You are trying to get a better feel for the effect of geometry and mass distribution on the moment of inertia. You have a solid disk and a thin ring, each of radius, r = 1.30 m, and mass, m = 73.0 kg. You mount both on fixed, horizontal frictionless axes about which they can spin freely. Then you spin them both. (a) How much work do you need to do to get each object to spin at 3.00 rad/s? (b) Let us assume that you have been causing them to spin by using a constant force applied tangentially to their circumferences. If the above speed is to be reached within 0.700 s, what is the magnitude of the force you need to apply to each object? (c) You next attempt to stop each object by pressing one finger on each side of each object, right at the outer edge. The coefficient of kinetic friction between each finger and the surface of each object is 0.300. Find the minimum force you have to apply to stop each object within 1.00 min.

Similar questions

Consider a person who is sitting on a frictionless rotating stool. The person initially has his arms outstretched and is rotating with an angular speed of 5.0 rad/s. He then pulls his arms close to his body, thus reducing his moment of inertia to 80% of the initial one. What is his final angular speed?
Ice skaters can increase the angular speed of their spins by pulling their arms towards their body. A skater with their arms extended has a moment of inertia of 2.49 kg m2 and a moment of inertia of 0.77 kg m2 after pulling their arms in. If a skater begins a spin with their arms extended such that they are rotating with an angular speed of 2.07 rad/s, what will their rotation speed be when they pull their arms in?
The figure above shows Einstein spinning on a platform. He is initially spinning at a rate of 1rev/s, and holding his hands a distance of R1 = 80.3 cm away from his body. He then pulls his arms in to a distance of R2 = 40cm, changing his rotational speed. In this problem you can model Einstein’s body as a cylinder with a moment of inertia I = 30MR2, where M is his mass (60kg), and R is the distance his hands are from his body. (Notice that the figure shows him holding weights, but we are going to assume they are massless, to make it simpler!)(a) If he draws his arms in very quickly, you can safely ignore any frictional force on the platform. Assuming this is true, how fast is he rotating after he draws his arms in? (b) In reality, after he draws his arms in friction will start to slow him down. If this small amount of friction is applying a torque of 4 Nm to the platform, how long would it take before Einstein stops moving?
A small 0.400-kg object moves on a frictionless horizontal table in a circular path of radius 3.30 m. The angular speed is 6.63 rad/s. The object is attached to a string of negligible mass that passes through a small hole in the table at the center of the circle. Someone under the table begins to pull the string downward to make the circle smaller. If the string will tolerate a tension of no more than 113N, what is the radius of the smallest possible circle on which the object can move?
There is a circular disk of radius 0.5 m and mass 2 kg. A child throws down a rock, hitting the edge of the disk perpendicularly with a force of 50 N. Thedisk doesn't break, but starts to spin. If the moment of inertia for the circular disk rotating about the center is 1/2M(r^2), What is the tangential acceleration of a point on the disk 0.05 m from the point of impact?
A playground merry-go-round of radius 4m has a moment of inertia of 324 kg m² and is rotating at 11 rev/min about a frictionless vertical axle. Facing the axle, a 25.0 kg child hops on and manages to sit down on the edge. What is the new rotational speed of the merry-go-round in rev/min?
A carousel has a radius of 1.60 m and a moment of inertia of 130 kg · m2. A girl of mass 43.0 kg is standing at the edge of the carousel, which is rotating with an angular speed of 3.10 rad/s. Now the girl walks toward the center of the carousel and stops at a certain distance from the center d. The angular speed of the carousel is now 5.4 rad/s. How far from the center, in meters, did the girl stop? The answer is NOT 1.21m
A uniform disk of mass m = 1.4 kg and radius R = 25 cm can rotate about an axle through its center. Four forces are acting on it as shown in the figure. Their magnitudes are F1 = 3.5 N, F2 = 3.5 N, F3 = 7.5 N and F4 = 3.5 N. F2 and F4 act a distance d = 2.5 cm from the center of mass. These forces are all in the plane of the disk. m = 1.4 kgR = 25 cmF1 = 3.5 NF2 = 3.5 NF3 = 7.5 NF4 = 3.5 Nd = 2.5 cm Write an expression for the magnitude τ1 of the torque due to force F1. Calculate the magnitude τ1 of the torque due to force F1, in N⋅m. Write an expression for the magnitude τ2 of the torque due to force F2. Calculate the magnitude τ2 of the torque due to force F2, in N⋅m. Write an expression for the magnitude τ3 of the torque due to force F3. Write an expression for the magnitude τ4 of the torque due to force F4. Calculate the magnitude τ4 of the torque due to force F4, in N⋅m. Calculate the angular acceleration α of the disk about its center of mass in rad/s2. Let…
A 20-kg piece of steel pipe that is 20 cm in diameter, 80 cm long, and 1 cm thick is rolling toward you at a speed of 3.0 m/s. (a)What is the magnitude and direction of the pipe’s angular velocity vector w? (b)What is the pipe’s rotational energy? (c) What is its total energy K + Urot?
We can model a small merry-go-round as a uniform circular disk with mass 88 kg and diameter 1.8 m. How many 22 kg children need to ride the merry-go-round, standing right at the outer edge, to double the moment of inertia of the system?
A playground merry-go-round of radius R = 1.20 m has a moment of inertia I = 245 kg · m2 and is rotating at 12.0 rev/min about a frictionless vertical axle. Facing the axle, a 22.0-kg child hops onto the merry-go-round and manages to sit down on the edge. What is the new angular speed of the merry-go-round (in rev/min)?
Please answer E16,E17