Each of two vectors,  and , lies along a coordinate axis in the xy plane. Each vector has its tail at the origin, and the dot product of the two vectors is

data-wiris-created="true" class="Wirisformula" />. Which possibility is correct?

A.

and  both lie along the positive x axis.

B.

 lies along the positive x axis.  lies along the negative x axis.

C.

 and  both lie along the positive y axis.

D.

lies along the negative x axis.  lies along the negative y axis.

E.

 lies along the positive y axis.  lies along the negative x axis.

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Answer: B

Physics & Space Science

The star Aldebaran is a red giant, and is much more luminous than the Sun. What conclusions can be drawn from this fact?

A. In the H-R diagram, Aldebaran is above and to the left of the Sun. B. Aldebaran is cooler than the Sun, but has larger diameter than the Sun. C. Aldebaran is a binary star. D. Aldebaran is hotter and much more massive than the Sun. E. None of these choices is correct.

A 60-W light bulb connected to a 120-V source draws a current of

A) 0.25 A. B) 0.5 A. C) 2.0 A. D) 4.0 A. E) more than 4 A.

Suppose you are facing a tall makeup mirror on a vertical wall. Fluorescent tubes framing the mirror carry a clockwise electric current. What is the direction of the field the current creates at a point on the wall outside the frame to the right?

1.left 2.right 3.horizontally toward you 4.horizontally away from you 5.no direction because the field has zero magnitude

An automobile initially moving 72. km/hr jams the brakes and skids to a stop in a distance of 24. meters on a dry pavement but stops in 81.6 m for a wet pavement (the auto weighs 2211. lbs, neglect reaction delay)

(a) What is the coefficient of friction for dry weather? (b) What is the coefficient in wet weather conditions? (c) Is this the STATIC or the KINETIC coefficient?