It would have helped to answer this question, if there were some options to choose from. I am answering the question based on what i understood. I hope that it helps you. The teeth rip and grind food into small chunks. This is also the main function of the teeth and it does help in the digestion of the food we take.
        
             
        
        
        
The normal force acts to counter the gravitational force, that is the upward direction.
        
             
        
        
        
Answer:
After 4 s of passing through the intersection, the train travels with 57.6 m/s
Solution:
As per the question:
Suppose the distance to the south of the crossing watching the east bound train be x = 70 m
Also, the east bound travels as a function of time and can be given as:
y(t) = 60t
Now,
To calculate the speed, z(t) of the train as it passes through the intersection:
Since, the road cross at right angles, thus by Pythagoras theorem:


Now, differentiate the above eqn w.r.t 't':


For t = 4 s:

 
        
             
        
        
        
Using the kinematic equation d =  V_0 * t  + 1/2 * a * t^2, where d is height you can rewrite this to be d = 1/2*g*t^2 or 4.9t^2
g = a because this is a free fall 
d = 1/2 * 9.81m/s^2 * 2.5^2
d = 30.65625m
d = 30.7m
        
             
        
        
        
He thermal velocity or thermal speed is a typical velocity of the thermal motion of particles which make up a gas, liquid, etc. Thus, indirectly, thermal velocity is a measure of temperature. Technically speaking it is a measure of the width of the peak in the Maxwell–Boltzmann particle velocity distribution.