Question

If a force of 200 newtons is required to move a wagon up a frictionless hill at constant speed, the force needed to left the wagon roll downhill at constant speed is________.

Answer 1

Step 1: Given.

A force of 200 newtons is required to move a wagon.

Step 2: Finding the force needed to leave the wagon to roll downhill at a constant speed.

Because it is traveling at a constant speed, the net force is zero.

There are forces acting on it;

1. Our force
2. Gravitation force

Then,

$0=ma+mg$(acceleration due to gravity)

$0=200+-10m$(round off of g)(- as it is opposing gravity)

$$\begin{gathered} -200=-10m \\ m=\frac{-200}{-10} \\ m=20kg \end{gathered}$$

While the wagon is falling apart once again.

$$\begin{gathered} 0=f+mg \\ 0=f+20\times 10 \\ 0=f+200 \\ f=-200N \end{gathered}$$

Then, 200 N in the opposite direction of the motion.