Asked by raquel
A rifle is aimed horizontally at a target 50 m away. The bullet hits the target 2.4 cm below the aim point.
Part A
What was the bullet's flight time? Neglect the air resistance
Part B
What was the bullet's speed as it left the barrel?
Part A
What was the bullet's flight time? Neglect the air resistance
Part B
What was the bullet's speed as it left the barrel?
Answers
Answered by
MathMate
In the absence of air resistance we can split the movement of the bullet into the vertical and horizontal components.
The former is a free-fall.
Using the kinematics equation below, we can solve for the time it takes to free-fall through 2.4 cm:
S=(v0)t+(1/2)at^2
with
v0=initial (vertical) velocity = 0
a=acceleration due to gravity=-9.81 m/s^2
s=-0.024 m
solve for t to get
t=sqrt(2*0.024/9.81)=0.07 s
If the bullet covered 50m in 0.07s, you can calculate the bullet's muzzle speed, in m/s.
The former is a free-fall.
Using the kinematics equation below, we can solve for the time it takes to free-fall through 2.4 cm:
S=(v0)t+(1/2)at^2
with
v0=initial (vertical) velocity = 0
a=acceleration due to gravity=-9.81 m/s^2
s=-0.024 m
solve for t to get
t=sqrt(2*0.024/9.81)=0.07 s
If the bullet covered 50m in 0.07s, you can calculate the bullet's muzzle speed, in m/s.