Question 1
A ball falls straight down in the xy plane. Its momentum is shown
by the red arrow. What is the direction of the ball's angular
momentum about location A?
1) +x
2) –x
3) +y
4) –y
5) +z
6) –z
(z-axis points
7) zero magnitude out of page)
Question 2
A ball falls straight down in the xy plane. Its momentum is shown
by the red arrow. What is the ball's z component of angular
momentum about location A?
1) +10
2) –10
3) +40
4) –40
5) 0
(z-axis points
out of page)
or
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Question 2
A ball (mass m = 2 kg) is falling toward the earth. At some instant,
when it is 6 meters from the ground, it has a speed of 5 m/s. At
that moment, what is its angular momentum about point A, which
is 4 meters to the left of the ball’s future point of impact?
1) +10
2) –10
3) +40
4) –40
5) 0
(z-axis points
out of page)
You can do this with the parallelogram method. Using geometry,
r sin (theta) = r (perp). r (perp) * p = 40 kg m/s gives the magnitude.
Using RHR we get the direction to be –z.
Question 3
A planet orbits a star, in a circular orbit in the xy plane.
Its momentum is shown by the red arrow.
What is the direction of the
angular momentum of the planet?
1) same direction as p
2) opposite to p
3) into the page
4) out of the page
5) zero magnitude
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Question 4
A planet orbits a star, in a circular orbit in the xy plane.
Its momentum is shown by the red arrow.
1) +x
2) –x
3) +y
4) –y
5) +z
6) –z
7) zero
(z-axis points
magnitude
out of page)
Question 5
A comet orbits the Sun, in an elliptical orbit in the xy plane. The
red arrow indicates its momentum. Which arrow best shows the
direction of the vector rA , where A is at the center of the Sun? 8
Question 6
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A comet orbits the Sun, in the xy plane. Its momentum is shown by
the red arrow. What is the direction of the comet's angular
momentum about the Sun?
1)
2)
3)
4)
5)
same direction as p
opposite to p
into the page
out of the page
zero magnitude
Question 7
A comet orbits the Sun, in the xy plane. Its momentum is shown by
the red arrow. What is the direction of the comet's angular
momentum about the Sun?
1) +x
2) –x
3) +y
4) –y
5) +z
6) –z
7) zero
(z-axis points
magnitude
out of page)
Question 8
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A comet orbits the Sun, in the xy plane. Its momentum is shown by
the red arrow. What is the direction of the comet's angular
momentum about the Sun?
1) +x
2) –x
3) +y
4) –y
5) +z
6) –z
7) zero
(z-axis points
magnitude
out of page)
Question 9
A comet orbits the Sun in the xz plane. Its momentum is shown by
the red arrow. What is the direction of the comet's angular
momentum about the Sun?
1)
2)
3)
4)
5)
6)
7)
+x
–x
+y
–y
+z
–z
zero magnitude
Question 10
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If an object is traveling at a constant speed in a vertical circle, how
does the object's angular momentum change as the object goes
from the top of the circle to the bottom of the circle?
1) L increases.
2) L decreases.
3) L stays the same, but the direction of L changes.
4) The direction and magnitude of L remain the same.
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