A worker pulls a 350-N packing crate at constant velocity across a rough floor by exerting a force F = 200.0 N at an angle of 30.0° above the horizontal. What is the coefficient of kinetic friction of the floor?
a. 0.793
b. 0.693
c. 0.593
d. 1.386
e. 0.400
b
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Answer the following statement(s) true (T) or false (F)
1. Since an object’s ends do not move in its rest frame, the events used to mark out an object’s length in that frame do not have to be simultaneous: the distance between them is the object’s rest length whether they are simultaneous or not.
2. An object’s length would be negative in a frame where it travels faster than the speed of light.
3. Suppose an object is in a frame where it is moving at speed and its length is L0 at that speed. If we double the speed 
then the object’s length is compressed by a factor of two
.
4. In the pole and barn problem, the barn never actually encloses the pole in the ground frame.
5. We can define a moving object’s length to be its speed times the time it takes to pass a given point
Which of the following statements about eclipses is true?
A. A partial solar eclipse happens every month, but not the total solar eclipse. B. A total solar eclipse is visible from any location on the day-side of Earth. C. A lunar eclipse is visible from any location on the night-side of Earth. D. All of these choices are correct.
As more lamps are put into a series circuit, the overall current in the power source
A) increases. B) decreases. C) stays the same.
Where does most rainfall on Earth finally end up before becoming rain again?
A) underground B) in lakes C) in the oceans D) on the ground surface