Answer:

Explanation:
From the question we are told that
Temp of first bolts
Temp of 2nd bolt 
Generally the equation showing the relationship between heat & temperature is given by

Generally heat released by the iron bolt = heat gained by the iron bolt
Generally solving mathematically





Therefore
is the final temperature inside the container
Answer:
b)
Explanation:
By convention, the electric field lines (which are tangent to the direction of the electric field at a given point) always begin at positive charges, and finish at negative charges.
This is a consequence of the convention that states that the electric field has the direction of the trajectory of a positive test charge when released from rest in an electric field.
(As the positive charge would move away from positive charges and would be attracted by negative ones).
So, the combination of answers that is true is b) (positive, negative, positive).
10km/10min is a legitimate speed. So is meters/sec, km/hour (kph), etc.
Kph is very common for vehicles:
10 km/10 min (60 min/hr) = 60 kph
Force=mass x acceleration
f= 0.5 x40
f=20N