Answer:
0.009 N, repulsive
Explanation:
The electrostatic force between two electric charges is given by:

where
k is the Coulomb's constant
q1 and q2 are the two charges
r is the separation between the two charges
In this problem, we have
are the two charges
r = 4.5 m is their separation
Substituting into the equation, we find

Moreover, the force is repulsive. In fact, the following rules apply:
- When two charges have same sign, they repel each other
- When two charges have opposite signs, they attract each other
Answer:
A). 1.9 cm
Explanation:
m = Mass of brick = 12 kg
g = Acceleration due to gravity = 9.81 m/s²
r = Radius of hose
A = Area = 
F = Force = 
Let us assume that the pressure required to lift the brick would be atmospheric pressure

The radius of the hose should be 1.9 cm
Explanation:
Fe₂O₃ + CO → Fe₃O₄ + CO₂
Balancing the equation above, we can derive simple mathematical equations that are very easy to solve.
aFe₂O₃ + bCO → cFe₃O₄ + dCO₂
a,b,c and d are the coefficients needed to balance the equation above;
Conserving Fe; 2a = 3c
O: 3a + b = 4c + 2d
C: b = d
let a = 1;
c = 
Since b = d
3a + d = 4c + 2d
3a = 4c + 2d - d
3a = 4c + d
a = 1, c = 
3 = 4 x
+ d
d = 
b = 
multiplying a, b, c and d by 3:
a = 3 b = 1 c = 2 and d = 1
3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂
Learn more:
Balanced equation brainly.com/question/2612756
#learnwithBrainly
Answer:
Explanation:
wavelength, λ = 3.4 m
wavelength, λ' = 3.3 m
Speed, v = 340 m/s
f = v / λ = 340 / 3.4 = 100 Hz
f' = v / λ' = 340 / 3.3 = 103.03 Hz
Frequency of beat, n = f' - f = 103.03 - 100 = 3.03 Hz