John is pushing a wheelbarrow filled with sand on a building site. The total mass of the wheelbarrow and its contents is 30kg. When he applies a force of 20N ;the wheelbarrow moves forward at a constant speed
(1)what is the magnitude of the friction between the wheels and the ground? Explain your answers
(2)draw a labelled freebody diagram of all the force that act on the wheelbarrow
1. a=0 because it moves with a constant speed
2.