Hi there!
We can begin by finding the acceleration of the block.
Use the kinematic equation:

The block starts from rest, so:

Now, we can do a summation of forces of the block using Newton's Second Law:

mb = mass of the block
T = tension of string
Solve for tension:

Now, we can do a summation of torques for the wheel:

Rewrite:

We solved that the linear acceleration is 1.5 m/s², so we can solve for the angular acceleration using the following:

Now, plug in the values into the equation:

<u>Answer:</u>
Yes
<u>Explanation:</u>
Average velocity is the ratio of total displacement and time taken for that displacement:

This means if displacement is zero, then average velocity will also be zero.
Displacement is zero when an object moves some distance in one direction, and then moves the same distance but in the opposite direction.
∴ As it is possible for displacement to be zero, it is also possible for average velocity to be zero.
Answer:
W = 12.96 J
Explanation:
The force acting in the direction of motion of the sand paper is the frictional force. So, we first calculate the frictional force:
F = μR
where,
F = Friction Force = ?
μ = 0.92
R = Normal Force = 2.6 N
Therefore,
F = (0.92)(2.6 N)
F = 2.4 N
Now, the displacement is given as:
d = (0.12 m)(45)
d = 5.4 m
So, the work done will be:
W = F d
W = (2.4 N)(5.4 m)
<u>W = 12.96 J</u>