I have to do calculations based upon a bow shooting an arrow vertically, and I have to state any assumptions i'm making.
Am I right to cite air resistance as negligible; and that the displacement will start 2m above the ground (not at ground level)? The rest I'm ok with.
Yes, those are the assumptions.
Thank you very much
When performing calculations for a bow shooting an arrow vertically, it is important to make certain assumptions. Let's address the two assumptions you mentioned:
1. Negligible Air Resistance: In most introductory physics problems, air resistance is often assumed to be negligible unless specifically mentioned. By neglecting air resistance, you assume that the arrow's motion is only influenced by the force applied by the bowstring and the force due to gravity.
2. Initial Displacement: Assuming that the displacement starts 2 meters above the ground instead of at ground level is a reasonable choice. This assumption accounts for the fact that when an arrow is shot, it typically starts from a higher position, such as being drawn back on the bowstring before release.
It's important to be aware that these assumptions simplify the problem and may not represent real-world conditions with complete accuracy. However, they allow for easier calculations and provide a good approximation for many introductory physics problems involving bow and arrow.
Additionally, feel free to consider other assumptions that could be relevant to your specific problem, such as neglecting the effects of wind or assuming the arrow is shot from rest.