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A rifle is fired horizontally and travels 200.0 m before hitting the ground. The rifle barrel is 1.90 m from the ground. What speed must the bullet have been travelling at?

Answer :

MathPhys

Answer:

321 m/s

Explanation:

First, find the time it takes for the bullet to hit the ground.

Given (in the y direction):

Δy = 1.90 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: t

Δy = v₀ t + ½ at²

(1.90 m) = (0 m/s) t + ½ (9.8 m/s²) t²

t = 0.623 s

Next, find the horizontal velocity needed to travel 200.0 m in that time.

Given (in the x direction):

Δx = 200.0 m

t = 0.623 s

a = 0 m/s²

Find: v₀

Δx = v₀ t + ½ at²

(200.0 m) = v₀ (0.623 s) + ½ (0 m/s²) (0.623 s)²

v₀ = 321 m/s

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