A railroad car of mass m and speed v collides and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system
A) is the same as before.
B) is half as much as before.
C) is one third as much as before.
D) is one fourth as much as before.
E) is one quarter as much as before.
B
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Camera Exposure: A zoom lens for a camera is adjusted to change its focal length from 38 mm to 304 mm. If the same amount of light is to be admitted to the lens in both cases, what is the final f-number if the original f-number was f/2.0?
Fill in the blank(s) with the appropriate word(s).
Which hypothetical universe will eventually contract, if there were no dark energy?
A) the universe with 1.5 times the critical density of matter B) the universe with 1.0 times the critical density of matter C) the universe with 0.5 times the critical density of matter
What is the binding energy of 12C? The mass of an atom of 12C is 12 u (exactly), of an atom of 1H is 1.007825 u, and of a neutron is 1.0086649 u.
A. 137 MeV B. 104 MeV C. 92.2 MeV D. 46.1 MeV E. 7.68 MeV
A uniform rod of mass M = 1.2 kg and length L = 0.80 m, lying on a frictionless horizontal plane, is free to pivot about a vertical axis through one end, as shown. The rotational inertia of the rod about this axis is given by (1/3)ML2. If a force (F = 5.0 N, ? = 40°) acts as shown, what is the resulting angular acceleration about the pivot point?
?
?
a.
16 rad/s2
b.
12 rad/s2
c.
14 rad/s2
d.
10 rad/s2
e.
33 rad/s2