The direction cosines of the vector (4i - 8j + 7k) are:
(A) (0.35, 0.81, -0.23)
(B) (0.52, 0.48, -0.21)
(C) (20.38, 0.21, -0.26)
(D) (0.35, -0.70, 0.62)
(D) (0.35, -0.70, 0.62)
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Indicate whether the statement is true or false
A supplier wants to make a profit by buying gold by weight at one altitude and selling it at the same price per newton at another altitude. The supplier should
A) buy at a high altitude and sell at a low altitude. B) buy at a low altitude and sell at a high altitude. C) disregard altitude because it makes no difference.
A long, straight wire (radius = 2.0 mm) carries a current of 2.0 A distributed uniformly over a cross section perpendicular to the axis of the wire. What is the magnitude of the magnetic field at a distance of 1.0 mm from the axis of the wire?
a. 0.40 mT b. 0.80 mT c. 0.10 mT d. 0.20 mT e. 0.75 mT
Radioactive Decay: The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is about 29 years. Suppose you have samples of both isotopes, and that they initially contain equal numbers of atoms of these isotopes. How will the activities (number of decays per second) of the samples compare?
A. The activity of the cobalt-60 sample will be greater. B. The activities cannot be compared without more information. C. The activities will be equal. D. The activity of the strontium-90 sample will be greater.