John pushes his brother Danny on a skateboard. John applies a force of 29 N and Danny's acceleration is 0.4 m/s

The combined mass of Danny and his skateboard = m = 72.5 kg

Explanation:

Force applied by john = F = 29N

Danny's Acceleration = a = 0.4 m/s

Combined mass of Danny and his skateboard = m = ?

According to Newton's second law of motion:

F = ma

m = F/a

m = 29/0.4

m = 72.5 kg

Hence, the combined mass of Danny and his skateboard will be 72.5 Kg.