It is dificult to stop an object with a lot of momentum becuase of inertia with means that a moving object will want to keep moving and a stationary object wil want to stay stationary and the larger the momentum of the moving object the harder it will be to stop
Answer:
Approximately 
assuming no heat exchange between the mixture and the surroundings.
Explanation:
Consider an object of specific heat capacity 
and mass 
. Increasing the temperature of this object by 
would require 
.
Look up the specific heat of water: 
.
It is given that the mass of the water in this mixture is 
.
Temperature change of the water: 
.
Thus, the water in this mixture would have absorbed :
.
Thus, the energy that water absorbed was: 
.
Assuming that there was no heat exchange between the mixture and its surroundings. The energy that the water in this mixture absorbed, 
, would be the opposite of the energy that the metal in this mixture released.
Thus: 
(negative because the metal in this mixture released energy rather than absorbing energy.)
Mass of the metal in this mixture: 
.
Temperature change of the metal in this mixture: 
.
Rearrange the equation to obtain an expression for the specific heat capacity: 
. The (average) specific heat capacity of the metal pieces in this mixture would be:
.
While the boy is sitting on the chair it creates a force downward on the chair and therefore the chair takes it and gives off the equal amount of force. So while he is putting force downward the chair is putting the same force upward.
L=wavelength
L=0.032
c=Lf
f=c/L
f=3e8/0.032
f=9.375GHz
