Incomplete question.The Complete question is here
A flat uniform circular disk (radius = 2.00 m, mass = 1.00 ✕ 102 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a friction less axis perpendicular to the center of the disk. A 40.0-kg person, standing 1.25 m from the axis, begins to run on the disk in a circular path and has a tangential speed of 2.00 m/s relative to the ground.
a.) Find the resulting angular speed of the disk (in rad/s) and describe the direction of the rotation.
b.) Determine the time it takes for a spot marking the starting point to pass again beneath the runner's feet.
Answer:
(a)ω = 1 rad/s
(b)t = 2.41 s
Explanation:
(a) initial angular momentum = final angular momentum
0 = L for disk + L............... for runner
0 = Iω² - mv²r ...................they're opposite in direction
0 = (MR²/2)(ω²) - mv²r
................where is ω is angular speed which is required in part (a) of question
0 = [(1.00×10²kg)(2.00 m)² / 2](ω²) - (40.0 kg)(2.00 m/s)²(1.25 m)
0=200ω²-200
200=200ω²
ω = 1 rad/s
b.)
lets assume the "starting point" is a point marked on the disk.
The person's angular speed is
v/r = (2.00 m/s) / (1.25 m) = 1.6 rad/s
As the person and the disk are moving in opposite directions, the person will run part of a revolution and the turning disk would complete the whole revolution.
(angle) + (angle disk turns) = 2π
(1.6 rad/s)(t) + ωt = 2π
t[1.6 rad/s + 1 rad/s] = 2π
t = 2.41 s
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Answer:
Satellite D has a mass (kg) of 500 and the distance from Earth (km) is 320.
Explanation:
The universal law of gravitation states that the force between two objects in the universe is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
We have to choose the satellite having greatest gravitational force with earth. In all options the distance from the earth is same i.e. 320 km. So, we have to select the satellite having maximum mass because the mass of the earth is constant.
Hence, the correct option is (D) " Satellite D has a mass (kg) of 500 and the distance from Earth (km) is 320 ".
Answer:
P = 12000 W
Explanation:
General data:
- F = 15000 N
- d = 40 m
- t = 50 s
- P = ?
Work is force times unit of distance. So in order to calculate the power we must first calculate the work.
Formula:
Replace and solve
once the work is found, we proceed to find the power according to the formula:
The power of the crane is <u>12000 Watts.</u>
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