Question

1. three blocks are pushed along a rough surface by a force with magnitude p, as shown below.

( diagram showing three blocks )

diagram of block 1, block 2, block 3 with force p pushing block 1

$f_c$ is the magnitude of the contact force between blocks 2 and 3, and $f_f$, $f_n$, and $f_g$ are the magnitudes of the friction, normal, and gravitational forces on block 1, respectively. which of the following is a correct free - body diagram for block 1?

a. diagram with $f_n$ up, $f_f$ left, $p$ right, $f_g$ down, $f_c$ right

b. diagram with $f_n$ up, $f_c$ left, $p$ right, $f_g$ down

c. diagram with $f_n$ up, $f_f$ left, $f_c$ right, $f_g$ down

d. diagram with $f_n$ up, $f_c$ right, $f_g$ down

Explanation:

1. Vertical forces on Block 3: The upward normal force $F_N$ balances the downward gravitational force $F_G$.
2. Horizontal forces on Block 3: Block 2 pushes Block 3 forward with the contact force $F_C$. Since the surface is rough, kinetic friction $F_f$ acts opposite to the direction of motion (leftward). The applied force $P$ does not act directly on Block 3.

Answer:

C. The free-body diagram with upward $F_N$, downward $F_G$, rightward $F_C$, and leftward $F_f$