The focal length of the lens of a simple camera is 40 mm. In what direction must the lens be moved to change the focus of the camera from a person 25 m away to a person 4.0 m away?

A) does not make any difference
B) sideways from the film
C) away from the film
D) towards the film


C

Physics & Space Science

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A steel tube with diameters d2 5 86 mm and d1 5 52 mm is twisted by torques at the ends. The diameter of a solid steel shaft that resists the same torque at the same maximum shear stress is approximately:

(A) 56 mm
(B) 62 mm
(C) 75 mm
(D) 82 mm

Physics & Space Science

Charge: A piece of plastic has a net charge of +2.00 ?C. How many more protons than electrons does this piece of plastic have? (e = 1.60 × 10-19 C)

A. 1.25 × 1013  B. 1.25 × 1019  C. 2.50 × 1013  D. 2.50 × 1019  E. 3.01 × 1023 

Physics & Space Science

For nearby spirals, their rotation curves help measure both light and dark matter

Indicate whether the statement is true or false

Physics & Space Science

Why did Ptolemy have the planets orbiting Earth on "circles upon circles" in his model of the universe?

A) to properly account for the varying distances of the planets from Earth B) to explain why Venus goes through phases as seen from Earth C) to explain why the Greeks were unable to detect stellar parallax D) to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky E) to explain why more distant planets take longer to make a circuit through the constellations of the zodiac

Physics & Space Science