Question

The average speed of a nitrogen molecule in air is about , and its mass is . (a) If it takes for a nitrogen molecule to hit a wall and rebound with the same speed but moving in the opposite direction, what is the average acceleration of the molecule during this time interval? (b) What average force does the molecule exert on the wall?

Answer 1

Answer:

a)  a = - 2 v₀ / t   b)  F = -2m v₀ / t

Explanation:

In this exercise, the molecular nitrogen reaches the wall with a velocity v and bounces with the same magnitude, but in the opposite direction, let's use kinematics to find the average acceleration

     $v_{f}$ = v₀ + a t

     a = ($v_{f}$ -v₀) / t

   $v_{f}$ = - v₀

     a = (- v₀ -v₀) t

    a = - 2 v₀ / t

b) to find the average force let's use the impulse concepts

     I = F t = Δp

    F t = m$v_{f}$- m v₀

    F = m (-v₀-v₀) / t

    F = -2m v₀ / t