Please help me. I don’t understand this.

Ft = 0[N]

Explanation:

To understand this problem we must perform an analysis of forces on the X axis, which coincides with the axis of forces of dogs.

In this way performing a sum of forces on the X-axis we will have (newton's third law):

From this analysis we can see that the resulting or total force is equal to zero, since there is no movement.

b.a device that inputs heat into a cool object

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.