23% 11: 09 AM LTE 1. Initially, a wheel rotating about a fixed axis at a constant angular acceleration has an angular velocity of 3.0 rad/sec. Two seconds later it has turned through 5.0 complete revolutions. Find the angular acceleration 2. Given the position vector r= 3i + 4j +5k and force F = 16i - 20j - 5 k, find the magnitude of the torque vectort so that t = r x F ? (Hint: use 3x3 matrix) A solid disk of mass equal to 7.0 kg and radius of 30 cm changes its rotations gradually from 45 rpm to 120 rpm in 5.0 sec 3. find the angular acceleration in rad/s. 4. how many revolutions has the disk turned in this 5.0 seconds? 5. find the change in rotational kinetic energy 6. find its moment of inertia in kgm2 7. find the magnitude of torque needed to make such a change in rpm. 8. find the tangential acceleration of a point P on the outer rim of the disk. 20t2 The fan blade in a jet engine rotates from rest with the angular acceleration a = 9. find the angular velocity as a function of time. 10. find the angular displacement as a function of time. 11. if the rotational inertia of the blade is 5.0 kgm2, find the work done on the blade in the first initial 3.0 seconds. (Hint: take t from zero to 3 and d0 = odt) A hollow sphere ( M = 3.0 kg and R = 60 cm ) is rolling down an inclined surface with a height of 2.0 meters and an inclined angle of 25 degrees. 12. find the moment of inertia of the sphere, in kgm2 13. find the speed of the center of mass when it reaches the bottom of the hill 14. find the total rotational kinetic energy at the bottom h ך
Kinematics
A machine is a device that accepts energy in some available form and utilizes it to do a type of work. Energy, work, or power has to be transferred from one mechanical part to another to run a machine. While the transfer of energy between two machine parts, those two parts experience a relative motion with each other. Studying such relative motions is termed kinematics.
Kinetic Energy and Work-Energy Theorem
In physics, work is the product of the net force in direction of the displacement and the magnitude of this displacement or it can also be defined as the energy transfer of an object when it is moved for a distance due to the forces acting on it in the direction of displacement and perpendicular to the displacement which is called the normal force. Energy is the capacity of any object doing work. The SI unit of work is joule and energy is Joule. This principle follows the second law of Newton's law of motion where the net force causes the acceleration of an object. The force of gravity which is downward force and the normal force acting on an object which is perpendicular to the object are equal in magnitude but opposite to the direction, so while determining the net force, these two components cancel out. The net force is the horizontal component of the force and in our explanation, we consider everything as frictionless surface since friction should also be calculated while called the work-energy component of the object. The two most basics of energy classification are potential energy and kinetic energy. There are various kinds of kinetic energy like chemical, mechanical, thermal, nuclear, electrical, radiant energy, and so on. The work is done when there is a change in energy and it mainly depends on the application of force and movement of the object. Let us say how much work is needed to lift a 5kg ball 5m high. Work is mathematically represented as Force ×Displacement. So it will be 5kg times the gravitational constant on earth and the distance moved by the object. Wnet=Fnet times Displacement.
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