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.

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be

the body's situation won't change the forces are equal opposit and on the same body