Answer:
A. -15.9 m/s²
Step-by-step explanation:
By the second law of newton, the net vertical force is equal to mass times vertical acceleration, so we can write the following equation:
![F_(net)=-F\sin35-mg=ma](https://img.qammunity.org/2023/formulas/physics/college/fxugd9l3y0c3jya7q3cl4tlo7c3v0f7tw2.png)
Where F is the constant force of 720 N, so Fsin(35) is the vertical component of this force, m is the mass, g is the gravity and a is the vertical acceleration. Solving for a, we get:
![a=(-F\sin35-mg)/(m)](https://img.qammunity.org/2023/formulas/physics/college/hgpfa4dn9ih1b9orp3nprgd30q8o4x7lbm.png)
Then, replace F = 720 N, m = 68 kg, and g = 9.8 m/s² to get:
![\begin{gathered} a=\frac{-720N(\sin35)-(68\text{ kg\rparen\lparen9.8 m/s}^2}{68\text{ kg}} \\ \\ a=-15.9\text{ m/s}^2 \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/uvrl3gki746c4hffbtpjot9jcr6md4uc0e.png)
Therefore, the vertical acceleration is
A. -15.9 m/s²