Answer:
0.237 (23.7 %)
Explanation:
The thermal efficiency of an engine is given by:

where
W is the useful work output of the engine
is the heat in input
Here we have:

and the work done is the total heat in input minus the heat exhausted:

So, the efficiency is
(23.7 %)
Answer:
some kind of chemical of which i do not know
Explanation:
If we want the object to continue to move at constant speed, it means that the resultant of the forces acting on the object must be zero. So far, we have:
- force F1 with direction north, of 10 N
- force F2 with direction west, of 10 N
The third force must balance them, in order to have a net force of zero on the object.
The resultant of the two forces F1 and F2 is

with direction at

north-west. This means that F3 must be equal and opposite to this force: so, F3 must have magnitude 14.1 N and its direction should be

south-east.