Question

based on this diagram, which quantities are equal to zero? choose all answers that apply: a $sumvec{f}_{x}$ b $sumvec{f}_{y}$ c $vec{a}_{x}$ d $vec{a}_{y}$

Explanation:

Step1: Analyze forces in x - direction

In the x - direction, there are forces $F_f$ and $F_a$. If the object is accelerating in the x - direction, $\sum\vec{F}_x=F_a - F_f
eq0$ and $\vec{a}_x
eq0$ in general. But if the object is in equilibrium in the x - direction, $\sum\vec{F}_x = 0$ and $\vec{a}_x=0$. Without more information, we can't be sure.

Step2: Analyze forces in y - direction

In the y - direction, the normal force $F_n$ acts upwards and the gravitational force $F_g$ acts downwards. If the object is not moving vertically, $\sum\vec{F}_y=F_n - F_g = 0$. According to Newton's second law $F = ma$, if $\sum\vec{F}_y = 0$, then $\vec{a}_y=0$.

Answer:

B. $\sum\vec{F}_y$, D. $\vec{a}_y$