An arrow is shot at a 30.0° angle with the horizontal. It has a velocity of 49 m/s.
(a) How high will the arrow go?
m
(b) What horizontal distance will it travel?
Initial vertical velocity = 49 sin 30.0 m/s
Initial horizontal velocity = 49 cos 30.0 m/s [and ignoring air resistance it's constant]
a = g = 9.8 m/s²
(a) Consider the vertical motion and take UP as the positive direction:
at the max height v(f) = 0 m/s
v(f)² = v(i)² + 2as
s = [v(f)² - v(i)²] / 2a
s = [0 - (49 sin 30.0)²] / [2 * (-9.8)]
s = 30.6 m
(b) Consider vertical motion to get the time of flight ... UP as positive direction:
s = v(i)t + (1/2)at²
assuming the arrows lands at the same level as it was when shot:
0 = 49 sin 30.0 t - 4.9t²
4.9t² - 49 sin 30.0 t = 0
t(4.9t - 49 sin 30.0) = 0
t = 0 [that's when it's shot] or 4.9t = 49 sin 30.0
t = 5 s
Horizontal range = v(horizontal) x time
so horizontal distance = 49 cos 30.0 x 5 = 212 m
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Verified answer
Initial vertical velocity = 49 sin 30.0 m/s
Initial horizontal velocity = 49 cos 30.0 m/s [and ignoring air resistance it's constant]
a = g = 9.8 m/s²
(a) Consider the vertical motion and take UP as the positive direction:
at the max height v(f) = 0 m/s
v(f)² = v(i)² + 2as
s = [v(f)² - v(i)²] / 2a
s = [0 - (49 sin 30.0)²] / [2 * (-9.8)]
s = 30.6 m
(b) Consider vertical motion to get the time of flight ... UP as positive direction:
s = v(i)t + (1/2)at²
assuming the arrows lands at the same level as it was when shot:
0 = 49 sin 30.0 t - 4.9t²
4.9t² - 49 sin 30.0 t = 0
t(4.9t - 49 sin 30.0) = 0
t = 0 [that's when it's shot] or 4.9t = 49 sin 30.0
t = 5 s
Horizontal range = v(horizontal) x time
so horizontal distance = 49 cos 30.0 x 5 = 212 m