The magnitude of force acting on the body is 36N
        
             
        
        
        
Answer:
A=
Explanation:
We have given power =40 W but only 10% of this power is used so actual power 
We know that from Stefan's law  where
 where  is Boltzmann constant which value is
 is Boltzmann constant which value is 
So  
 
A=
 
        
                    
             
        
        
        
Increase the force the engine provides and decrease the mass of the car