Those forces are exactly equal.
Gravity always works as a pair of <em>EQUAL</em> forces ... one in each direction
between two masses. Your weight on the Earth is exactly the same as
the Earth's weight on you.
For rotational equilibrium of the door we can say that torque due to weight of the door must be counter balanced by the torque of external force

here weight will act at mid point of door so its distance is half of the total distance where force is applied
here we know that

now we will have


so our applied force is 72.5 N
The amount of heat needed to increase the temperature of a substance by

is given by

where m is the mass of the substance, Cs is its specific heat capacity and

is the increase of temperature.
If we re-arrange the formula, we get

And if we plug the data of the problem into the equation, we can find the specific heat capacity of the substance:
Answer:
Temperature after ignition=7883.205 K
Explanation:
The number of moles is,
n=PV/RT
=(1.18x10^6)(47.9x10^-6)/8.314(325)
= 0.0209 moles
a) In this process volume is constant
Q=U
=nCv.dT
dT= Q/nCv
=1970/(1.5x8.314)(0.0209)
= 7558.205 K
The final temperature is,
= 7558.205+325
= 7883.205 K