Answer:
a

b

Explanation:
Generally the force of attraction between this two irons is mathematically represented as
![F = \frac{k * [Q_{Li} ] * [Q_{O} ] }{ r^2}](https://tex.z-dn.net/?f=F%20%3D%20%20%5Cfrac%7Bk%20%2A%20%20%5BQ_%7BLi%7D%20%20%5D%20%2A%20%5BQ_%7BO%7D%20%20%5D%20%20%7D%7B%20r%5E2%7D)
Here k is known as the proportionality constant with value 
substituting -2 for
i.e the charge on oxygen , +1 for
i.e the charge on Lithium and
for r
So


Generally the force of repulsion will be the magnitude but different direction to the force o attraction
So Force of repulsionn is

Explanation:
Given that,
Weight of the engine used to lift a beam, W = 9800 N
Distance, d = 145 m
Work done by the engine to lift the beam is given by :
W = F d

Let W' is the work must be done to lift it 290 m. It is given by :

Hence, this is the required solution.
Answer:
a) θ₁ = 23.14 °
, b) θ₂ = 51.81 °
Explanation:
An address network is described by the expression
d sin θ = m λ
Where is the distance between lines, λ is the wavelength and m is the order of the spectrum
The distance between one lines, we can find used a rule of proportions
d = 1/600
d = 1.67 10⁻³ mm
d = 1-67 10⁻³ m
Let's calculate the angle
sin θ = m λ / d
θ = sin⁻¹ (m λ / d)
First order
θ₁ = sin⁻¹ (1 6.5628 10⁻⁷ / 1.67 10⁻⁶)
θ₁ = sin⁻¹ (3.93 10⁻¹)
θ₁ = 23.14 °
Second order
θ₂ = sin⁻¹ (2 6.5628 10⁻⁷ / 1.67 10⁻⁶)
θ₂ = sin⁻¹ (0.786)
θ₂ = 51.81 °
D, Mercury as a weaker gravitational pull! Due to mercury being farther from the sun and it being a smaller planet it has a weaker pull
dissipation is the answer ;(