The Physics
Hypertextbook
Opus in profectus

# Rotational Kinematics

## Problems

### practice

1. A rifle is a long gun whose barrel has been grooved or "rifled" on the inside with spiral channels. (For comparison, a long gun with a smooth bore is called a musket.) Bullets fired from a rifled barrel spin. This gives them greater stability in flight and thus greater accuracy when fired. Since 1964, the standard infantry weapon in the US Army has been the .22 caliber M16 rifle. Due to rifling, a bullet fired from an M16 rotates two and a half times on its journey from the breech to the muzzle. Given a barrel length of 510 mm and a muzzle velocity of 950 m/s, determine…
1. the average translational acceleration,
2. the average angular acceleration (in radians per second squared), and
3. the final angular velocity (in rotations per second)
2. Write something else.
3. Write something different.
4. Write something completely different.

### numerical

1. Earth
1. What's the angular speed of the Earth's rotation about its axis?
2. What's the angular speed of the Earth in its orbit around the sun?
2. Clock I
1. What's the angular speed of the second hand on an analog clock?
2. What's the angular speed of the minute hand on an analog clock?
3. What's the angular speed of the hour hand on an analog clock?
3. Clock II
1. If the hour and minute hands of a clock are aligned at 00:00 (midnight), at what time will they realign again?
2. If the hour, minute, and second hands of a clock are aligned at 00:00:00 (midnight), at what time will they realign again?
4. Clock III
1. To the nearest order of magnitude, what's the speed of the tip of the minute hand on a wall clock in a classroom?
2. To the nearest order of magnitude, what's the speed of the tip of the minute hand on a man's wristwatch?