The direction of friction force is always the opposite of the direction of the movement.
In this problem, we have an applied force of 20N and this creates a movement. Then, the friction comes in and applies a force of 2.4N.
Because they are in different directions, we need to subtract them:
We don't know the direction because there is no picture (at least I can't see ☺️). But the movement will be to the direction of the 20N.
Force and distance is the main criteria for the movement of the object. The work of the object can be defined as the ‘product’ of the force and distance.
The colors that you see on the CD are created by white light reflecting from ridges in the metal. When light reflects off or passes through something with many small ridges or scratches, you often get rainbow colors and interesting patterns. They are called interference patterns.
We Know, F = m*a
Here, F = 34 N
m = 213 Kg
Substitute their values in the equation,
34 = 213 * a
a = 34/213
a = 0.159 m/s²
So, your final answer & the acceleration of the object would be 0.159 m/s²
Hope this helps!