Question 8
On a graph of frictional force against applied force, the first part of the line rises at 45°, so that friction equals the applied force. What does that part of the graph represent?
The right answer is the one marked above.
Static friction, with the object still at rest. Along the whole of that stretch friction gives back exactly what is applied, so the forces balance and nothing moves.
Dynamic friction is the flat part after the peak — there friction stays the same however much harder you pull, so the line no longer rises.