A small 0.300 kg bird is flying horizontally at 3.50 m/s toward a 0.750 kg thin
ID: 1464108 • Letter: A
Question
A small 0.300 kg bird is flying horizontally at 3.50 m/s toward a 0.750 kg thin bar hanging vertically from a hook at its upper end, as shown in the figure below
A)
When the bird is far from the bar, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point A ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative.
Part B
When the bird is far from the bar, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point B ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative
Part C
When the bird is far from the bar, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point C ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative.
Part D
When the bird is just ready to hit the bar, but is still flying horizontally, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point A ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative.
Part E
When the bird is just ready to hit the bar, but is still flying horizontally, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point B ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative.
Part F
When the bird is just ready to hit the bar, but is still flying horizontally, what are the magnitude and direction (clockwise or counterclockwise) of its angular momentum about a horizontal axis perpendicular to the plane of the figure and passing through point C ?
Let counterclockwise angular momentum be positive, clockwise angular momentum be negative
Explanation / Answer
A)
The angular momentum is the linear momentum times the normal (perpendicular) distance to the line of motion: Linear momentum = 0.300*3.50; the distance to A = 1.50 m; angular momentum = 1.58 kg*m²/s; the direction is counterclockwise
B)
The linear momentum is the same, but the normal distance to point B is zero, so the angular momentum is zero
C)
The linear momentum is the same, but the distance to C is 1.60 - 1.50 = 0.30 m; so the angular momentum is 0.315 kg*m²/s; The direction is clockwise