Why Is the Net Force on Both Cars Zero Despite Different Speeds?

[Skittles]

I don't understand this:

A slow car moves at a steady 10 km/hr down a straight highway while another car zooms past at a steady 120 km/hr. Which car is has the greater net force on it?

The answer is neither, because the net force on each car is zero.

Why is it zero?

 

[mbrmbrg]

Look at the definition of force.

 

[kyle8921]

The net force on an object is the sum of all the forces acting on it. In this scenario, both cars are moving at a constant velocity, which means that the net force acting on them must be zero. This is because the forces acting on the cars, such as friction and air resistance, are balanced and cancel each other out. If there was a greater net force on one car, it would accelerate and its velocity would change. Therefore, in this scenario, the net force on both cars is zero.