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
Answer : The correct option is, (C) 17 m/s
Explanation :
Formula used :
where,
K.E = kinetic energy = 6.8 J
m = mass of object = 46 g = 0.046 kg (1 kg = 1000 g)
v = velocity
Now put all the given values in the above formula, we get:
Therefore, the ball's velocity be as it leaves the cannon is, 17 m/s
Answer:
Frequency required will be 2421.127 kHz
Explanation:
We have given inductance 
Current in the inductor 
Voltage v = 13 volt
Inductive reactance of the circuit 
We know that
f = 2421.127 kHz
Answer:
1000 Hz
Explanation:
<em>The frequency would be 1000 Hz.</em>
The frequency, wavelength, and speed of a wave are related by the equation:
<em>v = fλ ..................(1)</em>
where v = speed of the wave, f = frequency of the wave, and λ = wavelength of the wave.
Making f the subject of the formula:
<em>f = v/λ.........................(2)</em>
Also, speed (v) = distance/time.
From the question, distance = 900 m, time = 3.0 s
Hence, v = 900/3.0 = 300 m/s
Substitute v = 300 and λ = 0.3 into equation (2):
f = 300/0.3 = 1000 Hz
