Name:________________________________ Problem set 3B
due in class: Wednesday, February 11
copyright © 2009 George Gollin Physics 325, UIUC, spring 2009
1
4. Fake and fake again.
The president of Euclid University receives a gift serving platter from the Republic of Lomar. The grotesque, but
expensive object is made from the fusion of two equilateral ceramic triangles with embedded clocks, as shown in the
following diagram. In order to render it into a more pleasing shape, the President launches it at high speed so that its
velocity is parallel to a straight line drawn through the centers of the clocks. After launching, a staff person riding
along with the serving platter (re)synchronizes the clocks in the rest frame of the platter. The velocity is chosen so
that the platter is square in shape, with equal lengths of the diagonals connecting the two corners.
a. Calculate v.
b. Assuming the clock at the center of the platter reads 0t
=
at the instant shown in right side of the figure,
determine the readings on the other two of the platter’s clocks as observed from a frame in which the moving platter
is square.
5. Perhaps you prefer choucroute?
The Urken’s Deli & Hardware Emporium high-performance delivery team makes a bratwurst resupply run for the
first (and only) St. Regis University alumni reunion. Two relativistic UD&HE FlashBuzzards arm themselves with
sausages, intending to drop their loads into a pair of sauerkraut tubs placed at opposite ends of an athletic field
owned by a legitimate university, but rented for the occasion by St. Regis. The setup is shown in the figure below.
The FlashBuzzard pilots maintain a separation of 1000 feet between their bratwurst loads in their rest frame.
(Naturally, their clocks are synchronized in this frame.) Large tubs of sauerkraut are at rest on the athletic field,
separated by 1200 feet. They too are equipped with (synchronized) clocks. When the clock on FlashBuzzard II reads
0t= it successfully releases its bratwurst load into the left tub of pickled cabbage. If the FlashBuzzards are
travelling at speed 0.8c, what will the clock on FlashBuzzard I read when it drops its cargo into the other tub?
…problem set continues on the other side…
a
a a
a a
a
v
Before After
? ?
F
lashBuzzard I
I
F
lashBuzzard
I
?
v v
