A horizontal force of 25 N is required to push a wagon across a sidewalk at a constant speed.

a. What is the net (unbalanced) force acting on the wagon?

b. What is the value of the force of friction acting on the wagon?

c. If the force on the box increased to 30 N, use Newton's law to explain what the effect would be.

a. The net force acting on the wagon is zero

b. The value of the force of friction is 25 N

c. The effect would be is the frictional force must be increase

Explanation:

Lets explain how to solve the problem

A horizontal force of 25 N is required to push a wagon across a sidewalk

at a constant speed

a.

→ Constant speed means acceleration is zero

→ Force = mass * acceleration

→ Force = mass * 0

→ Force = 0

The net force acting on the wagon is zero

b.

The wagon moves with constant speed, then

→ ∑ force = 0

There are two forces acting on the wagon external force of 25 N,

and the frictional force which is opposite to the direction of motion

→ 25 - Frictional force = 0

→ Frictional force = 25 N

The value of the force of friction is 25 N

c.

The force increased to 30 N

If the wagon still moves with constant speed

Due to Newton's law ∑ force in the direction of motion = mass *

acceleration, but acceleration is 0 because the wagon moves with

constant speed, then ∑ F = 0

So the frictional force must increase to 30 N

The effect would be is the frictional force must be increase

If the frictional force does not increase the wagon will accelerate