The speed of a moving bullet can be deter-
mined by allowing the bullet to pass through
two rotating paper disks mounted a distance
61 cm apart on the same axle. From the
angular displacement 14° of the two bullet
holes in the disks and the rotational speed
1436 rev/min of the disks, we can determine
the speed of the bullet.

Respuesta :

Answer:

v = 381 m/s

Explanation:

Linear Speed

The linear speed of the bullet is calculated by the formula:

[tex]\displaystyle v=\frac{x}{t}[/tex]

Where:

x = Distance traveled

t = Time needed to travel x

We are given the distance the bullet travels x=61 cm = 0.61 m. We need to determine the time the bullet took to make the holes between the two disks.

The formula for the angular speed of a rotating object is:

[tex]\displaystyle \omega=\frac{\theta}{t}[/tex]

Where θ is the angular displacement and t is the time. Solving for t:

[tex]\displaystyle t=\frac{\theta}{\omega}[/tex]

The angular displacement is θ=14°. Converting to radians:

[tex]\theta=14*\pi/180=0.2443\ rad[/tex]

The angular speed is w=1436 rev/min. Converting to rad/s:

[tex]\omega = 1436*2\pi/60=150.3776\ rad/s[/tex]

Thus the time is:

[tex]\displaystyle t=\frac{0.2443\ rad}{150.3776\ rad/s}[/tex]

t = 0.0016 s

Thus the speed of the bullet is:

[tex]\displaystyle v=\frac{0.61}{0.0016}[/tex]

v = 381 m/s