SOLUTION: 3. A bus moving in straight line at a speed of 20 m/s begins to slow down at a constant rate of 3 𝑚/𝑠2 each second. Find how far it goes before stopping?

Question 1161025: 3. A bus moving in straight line at a speed of 20 m/s begins to slow down at a constant rate of 3 𝑚/𝑠2 each second. Find how far it goes before stopping?
Answer by ikleyn(52776) (Show Source): You can put this solution on YOUR website!
.


Again, I will consider the problem as if it comes from Physics.


Then the breaking force is the product of the mass "m"  and acceleration "a"


          = ma.


while the kinetic energy is  .


Now apply the Energy conservation law: The kinetic energy is equal to the work of the force.


The force is  ,  and its work is the product of the force by the breaking distance "x", which is the unknown in this problem.


So you have this equation


     = m*a*x.


Cancel the mass in both side and obtain


    x =  =  =  = 66.666... = 66.7 meters (rounded).


ANSWER.  The breaking distance is  66.7 meters.

The other way to solve the problem is to use Calculus.

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