To find the mass m2, we can use Newton's second law of motion:

F = m * a

Where:
F = force applied (100 N)
m = mass (0.5 kg)
a = acceleration

Since we don't have the acceleration provided, we can rearrange the formula to solve for mass m2:

m2 = F / a

Given information:
F = 100 N
m1 = 0.5 kg
a = F / m1 = 100 N / 0.5 kg = 200 m/s^2

Now we can calculate the mass m2:

m2 = F / a
m2 = 100 N / 200 m/s^2
m2 = 0.5 kg

Therefore, the mass m2 is also 0.5 kg.