The gravitational force on the car is the force popularly known 
as the car's "weight".  Its magnitude is
            (9.8 m/s²) times (the car's mass, in kilograms) .
The unit of this quantity is [newton] .
        
             
        
        
        
Answer:
136000 J or 136 kJ
Explanation:
Formula
Heat = m * c * deltaH
Givens
m= 0.5 kg
c = 3400 J / (kg * oC)
Deltat = (100oC - 20oC)
deltat = 80oC
Solution
Heat = 0.5 kg * 3400 J/(kg* oC) * 80oC
Heat = 136000 Joules
Heat = 136 kg
Technically there is only 1 place of accuracy.
 
        
             
        
        
        
C
Pencil is mostly wood, only the tip is lead
        
                    
             
        
        
        
Answer:
C) The speed of the freight car decreases.
Explanation:
The speed of the freight car decreases, because the sand load increases the mass of the system.
Using the conservation of linear momentum

The linear momentum m*v is an amount that must be preserved, so this equality must be satisfied before and after the sand is added to the freight car.
Subindices 1 are for before the sand is added, and subindices 2 for after the sand is added.
In this case the mass in the second moment  is greater due to the mass added by the sand than the original mass
 is greater due to the mass added by the sand than the original mass  , so to maintain equality the speed in this situation must decrease.
, so to maintain equality the speed in this situation must decrease.
 
        
             
        
        
        
Answer:
laa a
Explanation:poque usairea  ye aire tienfe luza preopia mkr