What is the power of the lens that has a focal length of 40 cm?
A) -2.5 diopters
B) -4.0 diopters
C) +4.0 diopters
D) +2.5 diopters
E) +2.7 diopters
D
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Charge in an Electric Field: An electron is projected with an initial velocity v0 = 8.4 × 107 m/s along the y-axis, which is the centerline between a pair of charged plates, as shown in the figure. The plates are 1.0 m long and are separated by 0.10 m. A uniform electric field of magnitude E in the +x-direction is present between the plates. If the magnitude of the acceleration of the electron is measured to be 8.9 × 1015 m/s2, what is the magnitude of the electric field between the plates? (e = 1.6 × 10-19 C, melectron = 9.11 × 10-31 kg) 
A. 51,000 N/C B. 45,000 N/C C. 40,000 N/C D. 35,000 N/C E. 29,000 N/C
The event horizon of a black hole is
A) the surface below which no matter or energy can escape. B) the surface where light becomes trapped in a circular orbit around the black hole. C) the physical surface of the black hole. D) the point in time when a black hole comes into being.
First Law of Thermodynamics: An expansion process on an ideal diatomic ideal gas for which CV = 5/2 R has a linear path between the initial and final coordinates on a pV diagram. The coordinates of the initial state are: the pressure is 300 kPa, the volume is 0.030 m3, and the temperature is 390 K. The final pressure is 150 kPa and the final temperature is 340 K. What is the change in the internal (thermal) energy of the gas, during this process? (R = 8.31 J/mol ? K)
A. -2900 J B. -1700 J C. 2900 J D. 1700 J E. 0 J
A 2.0-kg block situated on a frictionless incline is connected to a light spring (k = 100 N/m), as shown. The block is released from rest when the spring is unstretched. The pulley is frictionless and has negligible mass. What is the speed of the block when it has moved 0.20 m down the plane?
a.
76 cm/s
b.
68 cm/s
c.
60 cm/s
d.
82 cm/s
e.
57 cm/s