The Hulk is standing on an old military turret (a big merry-go-round) at a military site. He is initially at rest. Thor hooks a cable to a pulley underneath the turret and pulls on it giving the Hulk a ride. The mass of the Hulk is mH = 293 kg. The mass of the turret is mD = 900 kg. The turret has a radius of rD = 15 m. The turret is a disk which has a rotational inertia of 1/2MR2 . The radius of the pulley is rp = 10 m and has a negligible rotational inertia. Consider the Hulk to be a point particle. (The rotational inertia of a point particle is MR2.) The Hulk stands at the edge of the turret. The cable is wrapped around the pulley 20 times so that the cable can pull on the turret for θ = 125.6 radians after which it gets released. The cable does not slip on the pulley. The magnitude of the angular acceleration of the turret and Hulk is 0.35 rad/s2 while the cable is still attached. What is the total rotational inertia of the turret and the Hulk combined? What is the magnitude of the torque provided by Thor on the turret? What is the magnitude of the force that Thor pulls with on the cable? What is the final angular speed of the turret and the Hulk after the cable is fully pulled out? What is the tangential speed of the Hulk? The Hulk walks to the center of the turret. What is the angular speed of the turret and Hulk now?
Angular Momentum
The momentum of an object is given by multiplying its mass and velocity. Momentum is a property of any object that moves with mass. The only difference between angular momentum and linear momentum is that angular momentum deals with moving or spinning objects. A moving particle's linear momentum can be thought of as a measure of its linear motion. The force is proportional to the rate of change of linear momentum. Angular momentum is always directly proportional to mass. In rotational motion, the concept of angular momentum is often used. Since it is a conserved quantity—the total angular momentum of a closed system remains constant—it is a significant quantity in physics. To understand the concept of angular momentum first we need to understand a rigid body and its movement, a position vector that is used to specify the position of particles in space. A rigid body possesses motion it may be linear or rotational. Rotational motion plays important role in angular momentum.
Moment of a Force
The idea of moments is an important concept in physics. It arises from the fact that distance often plays an important part in the interaction of, or in determining the impact of forces on bodies. Moments are often described by their order [first, second, or higher order] based on the power to which the distance has to be raised to understand the phenomenon. Of particular note are the second-order moment of mass (Moment of Inertia) and moments of force.
The Hulk is standing on an old military turret (a big merry-go-round) at a military site. He is initially at rest. Thor hooks a cable to a pulley underneath the turret and pulls on it giving the Hulk a ride. The mass of the Hulk is mH = 293 kg. The mass of the turret is mD = 900 kg. The turret has a radius of rD = 15 m. The turret is a disk which has a rotational inertia of 1/2MR2 . The radius of the pulley is rp = 10 m and has a negligible rotational inertia. Consider the Hulk to be a point particle. (The rotational inertia of a point particle is MR2.) The Hulk stands at the edge of the turret. The cable is wrapped around the pulley 20 times so that the cable can pull on the turret for θ = 125.6 radians after which it gets released. The cable does not slip on the pulley. The magnitude of the
What is the total rotational inertia of the turret and the Hulk combined?
What is the magnitude of the torque provided by Thor on the turret?
What is the magnitude of the force that Thor pulls with on the cable?
What is the final angular speed of the turret and the Hulk after the cable is fully pulled out?
What is the tangential speed of the Hulk?
The Hulk walks to the center of the turret. What is the angular speed of the turret and Hulk now?
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