All magnets have north and south poles. Opposite poles are attracted to each other, while the same poles repel each other. When you rub a piece of iron along a magnet, the north-seeking poles of the atoms in the iron line up in the same direction. The force generated by the aligned atoms creates a magnetic field.
Answer:
155.5 rev/min
Explanation:
First, we will calculate the initial moment of inertia I_o. We will consider the ice skater as a rod rotating around its axis. Then, we calculate the final moment of inertia I_f. In this occasion we consider the arms as a rod of length L that is horizontally positioned, L so that the length of an arm is L/2. We will call M_1 the mass that remains close to the rotation axis (90 percent) and M_2 the mass located at the arms (10 percent). Finally, we write the equation for the conservation of angular momentum and we solve for ω_f.
I_o=MR^2/2
=(45)(0.15)^2/2
=0.5 kgm^2
M_1=(0.9)(45)
=40.5 kg
M_2=(0.1)(45)
=4.5 kg
I_f=M_1*R^2/2+M_2*L^2/12
=1.1 kg m^2
I_f*ω_f=I_o*ω_o
ω_f = I_o*ω_o/ I_f
=155.5 rev/min
Answer:
2100 m
2804 g
4 '2 mm squares'
20,000 photos
Explanation:
1.5 km = 1500 m
1500 m + 600 m = 2100 m
2.8 kg = 2800 g
2800 g + 4 g = 2804 g
8mm tube / 2 mm squares
4 can fit
1 Gb = 1000 mb
40 Gb = 40,000 mb
40,000 mb / 2 mb = 20,000 photos
Answer:
the shortest distance to the obstruction is 0.431 m
Explanation:
We can see this system as an air column, where the plumber is open and where the water is closed, in the case when he hears the sound there is a phenomenon of resonance and superposition of waves with constructive interference.
For the lowest resonance we must have a node where the water is and a maximum where the plumber is a quarter of the wavelength
λ = ¼ L
If we are in a major resonance specifically the following resonance. We have a full wavelength plus a quarter of the wavelength
λ = 4L / 3
The general formula is
λ = 4L / n n = 1, 3, 5, 7,…
In addition the wave speed is the product of the frequency by the wavelength
v = λ f
Let's replace
v = (4L / n) f
L = v n / (4 f)
Now we can calculate the depth or length of the air column
If we have the first standing wave n = 1
L = 340 1 / (4 197)
L = 0.431 m
If it is the second resonance n = 3
L = 340 3 / (4 197)
L = 1.29 m
We can see the shortest distance to the obstruction is 0.431 m
