To find the mass of the puck, we can use Newton's second law of motion, which states that \( F = ma \), where:
- \( F \) is the force applied (in Newtons),
- \( m \) is the mass (in kilograms), and
- \( a \) is the acceleration (in meters per second squared).
Given:
- \( F = 20 , \text{N} \)
- \( a = 4 , \text{m/s}^2 \)
We can rearrange the formula to solve for mass \( m \):
\[ m = \frac{F}{a} \]
Substituting in the known values:
\[ m = \frac{20 , \text{N}}{4 , \text{m/s}^2} = 5 , \text{kg} \]
Therefore, the mass of the puck is 5 kg.