There are two external force acts on the chair.
1. The force due to earth gravity, acts in the downward direction.
2. Reaction force of the gravity, which acts in the Upward direction (Normal Force).
On every object, there is a force acts due to gravity of earth, which pulls the object towards the centre of earth, known as gravity force, always acts in the downward direction. Mathematically it's given as
F=mg
here, m is the mass of the object, and g is the acceleration of gravity.
To balance this gravity force, a counter force acts in the opposite direction, whose magnitude is equal to the force of gravity
Explanation:
Newton's second law:
∑F = ma
277 N − 245 N = (25 kg) a
a = 1.28 m/s²
Jane's mechanical energy at any time is

where

is the potential energy, while

is the kinetic energy.
Initially, Jane is on the ground, so the altitude is h=0 and the potential energy is zero: U=0. She's running with speed v, so she has kinetic energy only:

Then she grabs the vine, and when she reaches the maximum height h, her speed is zero: v=0, and so the kinetic energy becomes zero: K=0. So now her mechanical energy is just potential energy:

But E must be conserved, so the initial kinetic energy must be equal to the final potential energy:

from which we can find h, the maximum height Jane can reach:
I'm pretty your it's magnetism though. Like magnets
Answer:
The value is 
Explanation:
From the question we are told that
The radius of the inner conductor is 
The radius of the outer conductor is 
The potential at the outer conductor is 
Generally the capacitance per length of the capacitor like set up of the two conductors is
![C= \frac{2 * \pi * \epsilon_o }{ ln [\frac{r_2}{r_1} ]}](https://tex.z-dn.net/?f=C%3D%20%5Cfrac%7B2%20%2A%20%5Cpi%20%2A%20%5Cepsilon_o%20%7D%7B%20ln%20%5B%5Cfrac%7Br_2%7D%7Br_1%7D%20%5D%7D)
Here
is the permitivity of free space with value 
=> ![C= \frac{2 * 3.142 * 8.85*10^{-12} }{ ln [\frac{0.003}{0.001} ]}](https://tex.z-dn.net/?f=C%3D%20%5Cfrac%7B2%20%2A%20%203.142%20%20%2A%208.85%2A10%5E%7B-12%7D%20%20%7D%7B%20ln%20%5B%5Cfrac%7B0.003%7D%7B0.001%7D%20%5D%7D)
=> 
Generally given that the potential of the outer conductor with respect to the inner conductor is positive it then mean that the outer conductor is positively charge
Generally the line charge density of the outer conductor is mathematically represented as

=> 
=> 
Generally the surface charge density is mathematically represented as
here 
=> 
=> 