Not that we know of today, but we didn't know about dark matter until a few years ago.
Answer:
Terminal speed, v = 6901.07 m/s
Explanation:
It is given that,
Mass of the horizontal bar, m = 30 g = 0.03 kg
Length of the bar, l = 13 cm = 0.13 m
Magnetic field, 
Resistance, R = 1.2 ohms
We need to find the terminal speed oat which the bar falls. When terminal speed is reached,
Force of gravity = magnetic force
..................(1)
i is the current flowing
l is the length of the rod
Due to the motion in rods, an emf is induced in the coil which is given by :
, v is the speed of the bar


Equation (1) becomes,



v = 6901.07 m/s
So, the terminal speed at which the bar falls is 6901.07 m/s. Hence, this is the required solution.
The pyrite will be bigger, because its density is much lower.
I <em>do</em> know that the gold's volume will be 2.5906 (With a bunch more numbers after it)
50 divided by 19.3 = 2.5906
Answer:
Option D
2 m/s
Explanation:
The speed is given by distance/time
The complete wave has a distance of 8 m (This is the wavelength)
Time taken for complete wave is 4 s
Therefore, velocity= 8 m/ 4 s= 2 m/s
The amplitude is the distance between crest and trough hence 9 m- 6 m= 3 m
Frequency is 1/period and in this case period is 4 s hence frequency= 1/4= 0.25 Hz
Essentially, what we wanted is velocity
True, when charging a secondary cell, energy can be stored within a dielectric material using an electric field.
<h3>Relationship between dielectric material and electric field</h3>
The electric field in a capacitor separates the negative and positive charges in the dielectric material, this causes an attractive force between each plate and the dielectric.
The dielectric material can store electric energy due to its polarization in the presence of external electric field, which causes the positive charge to store on one electrode and negative charge on the other.
Thus, when charging a secondary cell, energy can be stored within a dielectric material using an electric field.
Learn more about dielectric material here: brainly.com/question/17090590