Exercise 6.6
Next, repeat step on a horizontal polished marble or tile floor. Does the stack of coins travel an even larger distance and its velocity decrease even more slowly? What conclusion do you draw from your observations? Before you release the stack of coins, it is stationary. It means that the forces acting upon it are balanced. Upon release, the force applied by you
NCERT’s answer
$\displaystyle 0$ N
The net force is zero, \(\displaystyle 0\ \text{N} \).
Mass \(\displaystyle m = 100\ \text{g} = 0.1\ \text{kg} \), and the velocity is constant at \(\displaystyle 0.5\ \text{m s}^{-1} \).
Constant velocity means no change in velocity, so \(\displaystyle a = 0\ \text{m s}^{-2} \).
By Newton's second law, \(\displaystyle F = ma = 0.1\ \text{kg} \times 0\ \text{m s}^{-2} = 0\ \text{N} \).