Hello!
[tex]\large\boxed{0.018 N}[/tex]
Begin by finding the acceleration of the puck. Use the kinematic equation:
[tex]d = v_{i} + \frac{1}{2}at^{2}[/tex]
The initial velocity is 0 m/s since the object was at rest, so we can rewrite the equation as:
[tex]d = \frac{1}{2}at^{2}[/tex]
Plug in the given distance and time:
[tex]1.25 = \frac{1}{2}a(5^{2})\\\\2.50 = 25a\\\\a = 0.1 m/s^{2}[/tex]
Find the net force using the formula F = m · a (Newton's Second Law)
F = 0.18 · 0.1
F = 0.018 N