1.A 3.9 kg stone is tied to a 5.8 m long string and swung around a circle at a c
ID: 2254836 • Letter: 1
Question
1.A 3.9 kg stone is tied to a 5.8 m long string and swung around a circle at a constant angular velocity 1.7 1/s. Find the magnitude of the torque about the origin
2.A uniform meter stick is placed on and parallel to the x axis, with the 50 cm mark at the origin. It is pivoted at the 50 cm mark. A 3.9 N force is applied at the 43 cm mark, and a -4.1 N force is applied at the 90 cm mark. Find the net torque on the rod.
3.
A thin disk, mounted on a frictionless vertical shaft of negligible rotational inertia, is rotating at 215 revolutions per minute. An identical disk (that is not initially rotating) is dropped onto the first disk. The frictional force between the disks causes them to rotate at a common angular velocity. Find this common angular velocity.
Use rad/s for your unit.
4.
A merry-go-round has a radius of 10 m and a moment of inertia of 663 kg.m2. It is initially spinning with an angular velocity ? = 1.4 rad/s when a 18 kg child crawls from the center to the rim. When the child reaches the rim, what is the angular velocity of the merry-go-round?
Use rad/s for your answer.
5.At the same instant that a 2.7 kg ball is dropped from 30 m above the Earth's surface, a second ball, with a mass of 8.8 kg, is thrown straight upward from the Earth's surface with initial velocity of 1.6 m/s. They move along nearby lines and pass without colliding. At the end of 3 s, what is the height above the Earth of the center of mass of the two-ball system?
6.
At the same instant that a motionless 9.6 kg ball is dropped from 27 m above the Earth's surface, a second ball, with a mass of 4.5 kg, is thrown straight upward from the Earth's surface with initial velocity of 21.1 m/s. They move along nearby lines and pass without colliding. At the end of 2.1 s, what is the velocity of the center of mass of the two-ball system?
Choose down as the -y direction.
7.
At the same instant that a 6.2 kg ball is dropped from 11 m above the Earth's surface, a second ball, with a mass of 2.2 kg, is thrown straight upward from the Earth's surface with initial velocity of 19 m/s. They move along nearby lines and pass without colliding. At the end of 2.3 s, what is the accleration of the center of mass of the two-ball system?
8.
Block A, with a mass of 2.4 kg, is stationary, while block B, with a mass of 8.6 kg, is moving at 8.1 m/s. What is the speed of the center of mass of this two-block system?
9.
A 932 kg rocket is motionless in space. To start moving, its main engine is fired for 7 s, during which time it ejects exhaust gases at 1205 m/s. At the end of this process it is moving at 17 m/s. What is the approximate mass of ejected gas?
10.
The center of mass of a system consisting of two spheres is moving in the +x direction with a speed of 6.6 m/s. One sphere has a mass of 9.8 kg and the other has a mass of 7.8 kg. What is the total momentum of the system?
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