Projectile Motion / Kinematics Question

[moto_za]

Would appreciate any help understanding how to answer the question below:

If a projectile leaves a railgun near the surface of Earth with a speed of 2 km/s horizontally, how far will it fall in .01 sec?

Answer is 4.9x10^-4

---

Members don't see this ad.

 

[milski]

The horizontal speed in this case does not matter. The vertical acceleration is 9.8 and the fall will be 0.5*9.8*0.01^2=4.9*10^-4

 

[moto_za]

The horizontal speed in this case does not matter. The vertical acceleration is 9.8 and the fall will be 0.5*9.8*0.01^2=4.9*10^-4

Thanks a lot for the response. I mistakenly used X = VT for this question. How did you know that the horizontal speed does not matter? I got tricked by the word horizontal in the question. Is there a way to know when to use which formula without getting tricked? TIA

 

[milski]

The question is asking how far [down] will the projectile fall.

 

[moto_za]

The question is asking how far [down] will the projectile fall.

Thanks!!