Collisions in Two Dimensions: An 80-kg man is skating northward and happens to suddenly collide with a 20-kg boy who is ice skating toward the east. Immediately after the collision, the man and boy are seen to be moving together at 2.5 m/s in a direction 60° north of east. How fast was the boy moving just before the collision?
Fill in the blank(s) with the appropriate word(s).
6.3 m/s
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A parallel plate capacitor has a dielectric with constant 3.5. The plates are circular with radius 0.07 m, and the separation gap is 0.375 mm. What energy may be stored in this capacitor if 1250 V is the applied voltage?
a. 
b. 
c. 
d. 
Two one-liter containers each contain 10 moles of a gas. The temperature is the same in both containers. Container A holds helium (molecular mass = 4 u), and Container B holds oxygen (molecular mass = 16 u). Which container has the higher pressure and by what factor?
a. Container A has 4 times the pressure of Container B. b. Container A has 2 times the pressure of Container B. c. Both containers have the same pressure. d. More information is needed to answer this question.
A 3.0-kg block slides on a frictionless 20° inclined plane. A force of 16 N acting parallel to the incline and up the incline is applied to the block. What is the acceleration of the block?
a. 2.0 m/s2 down the incline b. 5.3 m/s2 up the incline c. 2.0 m/s2 up the incline d. 3.9 m/s2 down the incline e. 3.9 m/s2 up the incline
If, at the instant of fission, the Ba and Kr fragments are spherical and just barely in contact,
what is the electrostatic potential energy of these two fragments? (1 eV = 1.60 × 10-19 J, e = 1.60 × 10-19 C, 1/4??0 = 8.99 × 109 N ? m2/C2 ) A) 270 MeV B) 250 MeV C) 230 MeV D) 260 MeV E) 240 MeV