I would say 648858. bc yes
Answer:
D) wood rubbed against a rough surface feels hot
Explanation:
The heat is transferred from one form of energy (friction of the wood being rubbed against the surface) to another (heat energy).
Answer:
(a) the force is 8.876 N
(b) the magnitude of each charge is 4.085 μC
Explanation:
Part (a)
Given;
coulomb's constant, K = 8.99 x 10⁹ N.m²/C²
distance between two charges, r = 10 cm = 0.1 m
force between the two charges, F = 15 N
when the distance between the charges changes to 13 cm (0.13 m)
force between the two charges, F = ?
Apply Coulomb's law;

Part (b)
the magnitude of each charge, if they have equal magnitude

where;
F is the force between the charges
K is Coulomb's constant
Q is the charge
r is the distance between the charges

Answer:
a
The radial acceleration is 
b
The horizontal Tension is 
The vertical Tension is 
Explanation:
The diagram illustrating this is shown on the first uploaded
From the question we are told that
The length of the string is 
The mass of the bob is 
The angle made by the string is 
The centripetal force acting on the bob is mathematically represented as

Now From the diagram we see that this force is equivalent to
where T is the tension on the rope and v is the linear velocity
So

Now the downward normal force acting on the bob is mathematically represented as

So

=> 
=> 
The centripetal acceleration which the same as the radial acceleration of the bob is mathematically represented as

=> 
substituting values


The horizontal component is mathematically represented as

substituting value

The vertical component of tension is

substituting value

The vector representation of the T in term is of the tension on the horizontal and the tension on the vertical is

substituting value
![T = [(0.3294) i + (3.3712)j ] \ N](https://tex.z-dn.net/?f=T%20%20%3D%20%5B%280.3294%29%20i%20%20%2B%20%283.3712%29j%20%5D%20%5C%20%20N)
If this case could ever happen, the speed would follow from this formula:

with f the frequency and lambda the wavelength. We are give a wavelength of 10m. The frequencies of the visible light can range between 400 to about 790 Terahertz, so let us pick a middle point of 600 THz ("green-ish") as a "representative."

The speed of such a wave would have to be 6e+15 m/s (which would be 7 orders of magnitude higher than the universal speed of light constant)