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[SOLVED] The speed of a bullet may be determined by allowing the bullet to pass throu
Hello! I am new here and this is my first time posting...I am working on a physics problem and I have been stumped on it for a while now. Any hints would be greatly appreciated.
The speed of a moving bullet can be determined by allowing the bullet to pass through two rotating paper disks mounted a distance d apart on the same axle. From the angular displacement Δθ of the two bullet holes in the disks and the rotational speed of the disks, we can determine the speed v of the bullet. Find the bullet speed for the following data:
d=80 cm, ω=900 rev/min, and Δθ=31º.
My initial thought was that I would need to use the rotational kinematics formulas in some way or another:
1. ω = ω(initial) + αt
2. θ = θ(initial) + 1/2(ω + ω(initial))t
3. θ = θ(initial) + ω(initial)t + 1/2αt^2
4. ω^2 = ω(initial)^2 + 2α(θ - θ(initial))
to somehow get t, and then use the horizontal displacement over t to find v, the velocity of the bullet.
Some of my thoughts: I do not know what alpha, the angular acceleration is, so I cannot use it in order to find t. This rules out equations 1, 3, and four, leaving me with equation 2 to work with. Only one angular velocity was given in the problem, so the omegas in the formula confuse me, and I'm not sure if I need to use the same number for omega initial and omega final, or if I am supposed to assume constant angular velocity at all. If so, I think I can use 0 as theta initial and the 31 degrees as theta final to find t.
If this is in fact the correct way to approach this problem (I have searched the chapter in the book and can't seem to find another approach), the last thing on my mind is the issue of radians and degrees. Should I change every aspect of the problem to radians, or to degrees? My initial impression was radians, but from the way I'm looking at it, I'm not sure if it would make a difference, or if there is a correct way to do this. I am again assuming that the velocity remains constant, so that is how I can find it, by dividing d by time.
ANY hint or small tip in the right direction would be greatly appreciated. Thanks ahead for any help.
Hello! I am new here and this is my first time posting...I am working on a physics problem and I have been stumped on it for a while now. Any hints would be greatly appreciated.
Homework Statement
The speed of a moving bullet can be determined by allowing the bullet to pass through two rotating paper disks mounted a distance d apart on the same axle. From the angular displacement Δθ of the two bullet holes in the disks and the rotational speed of the disks, we can determine the speed v of the bullet. Find the bullet speed for the following data:
d=80 cm, ω=900 rev/min, and Δθ=31º.
Homework Equations
My initial thought was that I would need to use the rotational kinematics formulas in some way or another:
1. ω = ω(initial) + αt
2. θ = θ(initial) + 1/2(ω + ω(initial))t
3. θ = θ(initial) + ω(initial)t + 1/2αt^2
4. ω^2 = ω(initial)^2 + 2α(θ - θ(initial))
to somehow get t, and then use the horizontal displacement over t to find v, the velocity of the bullet.
The Attempt at a Solution
Some of my thoughts: I do not know what alpha, the angular acceleration is, so I cannot use it in order to find t. This rules out equations 1, 3, and four, leaving me with equation 2 to work with. Only one angular velocity was given in the problem, so the omegas in the formula confuse me, and I'm not sure if I need to use the same number for omega initial and omega final, or if I am supposed to assume constant angular velocity at all. If so, I think I can use 0 as theta initial and the 31 degrees as theta final to find t.
If this is in fact the correct way to approach this problem (I have searched the chapter in the book and can't seem to find another approach), the last thing on my mind is the issue of radians and degrees. Should I change every aspect of the problem to radians, or to degrees? My initial impression was radians, but from the way I'm looking at it, I'm not sure if it would make a difference, or if there is a correct way to do this. I am again assuming that the velocity remains constant, so that is how I can find it, by dividing d by time.
ANY hint or small tip in the right direction would be greatly appreciated. Thanks ahead for any help.
