Answer: the friction force on the small block at t equals 1 second is 2N
Step-by-step explanation:
Given the data in the question;
from the slope in the graph provided, we will get the acceleration of the slab
At t = 1 seconds
Slope = acceleration = ( 1 - 0) / ( 2 - 0 ) = 1/2 = 0.5 m/s²
Force = ma = 4 × 0.5 = 2 N
so by Newton's third law
Force on block will be same which is 2N
Therefore the friction force on the small block at t equals 1 second is 2N