Question

A streamlined and compact projectile is launched from flat ground on a valley toward a distant hillside at an Army testing ground in Nevada. The projectile’s initial speed is vi = 150. m/s as it leaves the cannon. The initial angle of launch θi of the projectile is unknown. The projectile makes impact high on the distant hill a time t = 3.00 s after its departure. From GPS sensors we know that the site of impact is a straight-line horizontal distance of Δx = 360. m from the launch site, albeit an unknown height H above the launch site. Assume an idealized situation in which air resistance has no appreciable effect on the projectile’s trajectory.
a) What is vix , the x-component of the initial velocity vector?



b) Find the initial angle of launch θi of the projectile.


c) What is viy , the y-component of the initial velocity vector?


d) How high H above the launch site does the projectile land?



e) What is vfx , the x-component of the final velocity vector right before impact?

f) What is vfy , the y-component of the final velocity vector right before impact?

Answer 1

There is no acceleration in the horizontal direction so the horizontal component of velocity doesn't change during the projectile motion.

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