Question

What is the range of a bullet fired horizontally at a height of 1.5 m with an initial velocity of 120 m/s

A) -9.8 m/s^2
B) about 0.55 s
C) about 66.4 m
D) not enough info

I think it’s not enough info (D) because I don’t know how to solve this
Can someone pls help me. I’m probably wrong

Answer 1

C. 66.4 m

Because the horizontal acceleration is 0, use x = v(Δt) to find horizontal displacement (the range)

v = 120 m/s

Use t = (sqrt)Δy/(0.5[-9.81]) to find Δt

Δy = -1.5m (because it is *falling* from 1.5 meters, thus it is negative)

t = (sqrt)-1.5/(0.5[-9.81])
t = (sqrt)-1.5/-4.905
t = (sqrt)0.3058103
t = 0.553

Now substitute

x = v(Δt)
x = 120(0.553)
x = 66.36

66.36 is about 66.4

c: