2 Points
Friction between solids can be most accurately defined as the force that
opposes the sliding motion of two _ that are touching each other.
O
O
O
A. forces
B. weights
C. directions
O
D. surfaces
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diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

this would be about 43%