Mechanics | Relativity Answers

A turntable with a moment of inertia of 0.011 kg∗m2 rotates freely at 3.1 rad/s. A circular disk of mass 400 g and diameter 22 cm, and initially not rotating, slips down a spindle and lands on the turntable.

a) Find the new angular speed (rad/s)

b) what is the change in kinetic energy?

Two blocks with masses m1 = 3.8 kg and m2 = 5.6 kg are connected by a string that hangs over a pulley of mass M = 2.1 kg and radius R = 0.2 m as shown above. The string does not slip. Assuming the system starts from rest, use energy principle find the speed of m2 after it has fallen by 0.7 m. Treat the pulley as a disk.

At t = 0 s a flywheel is rotating at 25 rpm. A motor gives it a constant acceleration of 0.5 rad/s2 until it reaches 70 rpm. The motor is then disconnected. How many revolutions are completed at t = 21 s

Two particles with masses 2.3 kg and 6.6 kg are connected by a light rod of length 3.5 m. Find the moment of inertia of the system about an axis perpendicular to the rod and passing through:

a) the midpoint of the rod;
(I already found the answer for this one: 27.26 kg∗m^2)

but I don't know how to find the answer for b)

b) the center of mass of the system of particle

In the figure above, a 20 kg boom of length 4.5 m is supported by a cable that has a beraking tension of 750 N. The cable is perpendicular to the boom and is attached 3.375 m from the pivot. Find:
a) the maximum load that can be suspended from the end of the boom;
b) The magnitude of the vertical force exerted by the pivot at maximum load?
c) The magnitude of the horizontal force exerted by the pivot at maximum load?

Here's the picture http://gauss.vaniercollege.qc.ca/webwork2_course_files/NYAangoni/tmp/gif/1110231-2152-setrotational_equilibrium-prob1--vphys/Graphics/ch-12-e31.gif
Follow 2 answers

A ladder of mass M and length 4 m rests against a frictionless wall at an angle of 50 degrees to the horizontal. The coefficient of static friction between the ladder and the floor is 0.65. What is the maximum distance along the ladder a person of mass 15M can climb before the ladder starts to slip?

Two bodies of same mass tied with an inelastic string of length l lie together. One of them is projected vertically upwards with velocity root 6gl . Find the maximum height up to which the centre of mass of system of the two masses rises.

Two balls of equal masses are projected upward simultaneously, one from the ground with speed 50 m/s and other from a 40 m high tower with initial speed 30 m/s. Find the maximum height attained by their centre of mass.

A man whose mass is m kg jumps vertically into air from a sitting position in which his centre of mass is at a height h1 from the ground. When his feet are just about to leave the ground his centre of mass is h2 from the ground and finally rises to h3 when he is at the top of the jump. (a) What is the upward force exerted by the ground on him treating it as a constant? (b) Find work done by normal reaction from ground.

A body of mass 2 kg is moving under the influence of a central force whose potential energy is given by U (r) = 2r3 Joule. If the body is moving in a circular orbit of 5m,then find its energy.