Answer:
a. i His weight and the normal force on him due to the ground
ii The weight and the normal force are balance
b. There are four forces acting on him while he is walking. These are the backward push due to his leg on the ground and the frictional force between his feet in the horizontal direction and, his weight and normal force on his feet in the vertical direction.
Explanation:
a. i Describe the forces that are acting on a person who is standing still on a sidewalk
His weight and the normal force on him due to the ground act on him while the person is standing on the sidewalk
ii. identify whether the forces are balanced or unbalanced.
The weight and the normal force are balance because, the person does not move in the vertical or horizontal direction.
b. Describe how the forces would change if the person started walking.
When the person starts walking, the backward push due to his leg on the ground and the frictional force between his feet and the ground now acts on him in the horizontal direction. The frictional force acts in the forward direction and tends to move him forward. His weight and normal force on his feet still act vertically and are both balanced since he does not move in the vertical direction.
<u>So, there are four forces acting on him while he is walking. These are the backward push due to his leg on the ground and the frictional force between his feet in the horizontal direction and, his weight and normal force on his feet in the vertical direction.</u>
