Answer:
A
Explanation:
1. When the block moves across a table top, F(pulling) = - F(frictional).
Sum of this forces = 0, so the block moves with uniform speed.
2. When the block is pulled on top of the table covered with beads
F(pulling) > - F(frictional).
So, the sum of forces (∑F) is a number that is more than 0 and directed to the direction of movement.
So, a = ∑F / m is positive and constant. Speed is increasing because
v(t) = v(0)+at
a is constant and directed forward.
That means a is acceleration, and constant.
