Question

4. In the Exploration, the sled does not move at all when two equal forces are applied
opposing directions. Explain the reason behind this.

Answer 1

Answer:

The net force is zero, so the acceleration is zero

Explanation:

Newton's second law states that the acceleration of an object is proportional to the net force applied to it, according to the equation:

$\sum F = ma$ (1)

where

$\sum F$ is the net force on the object

m is the mass of the object

a is its acceleration

In this problem, we have a sled acted upon two forces, $F_1, F_2$. So the net force on the sled is

$\sum F = F_1 + F_2$ (2)

however, we are told that the two forces are equal in magnitude but in opposite directions, so

$F_1 = F\\F_2 = -F$

So, eq.(2) becomes

$\sum F = F+(-F) = 0$

and so eq.(1) becomes

$\sum F = ma = 0$

which means

$a=0$

so the acceleration of the sled is zero, and if the sled was at rest, it will not move.