Collisions between galaxies
A) are much rarer than collisions between stars.
B) can turn elliptical galaxies into spirals.
C) cause large numbers of stars to collide and explode.
D) cause the gas and dust clouds to collide, leading to rapid star formation.
E) are the best explanation for gamma-ray burst events.
D
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A catapult fires an 800-kg rock with an initial velocity of 100 m/s at a 40° angle to the ground. The magnitude of the vertical impulse the catapult receives from the rock is
A.
s.B.
s.C.
s.D.
s.E.
s.Light precedes through three polarizing sheets. Unpolarized light enters the 1st sheet and the resultant vertically polarized beam continues through the 2nd and 3rd
The 2nd sheet has its transmission axis at 50.° with respect to the 1st, and the 3rd is at 70.° with respect to the 1st. (a) What percent of the original intensity emerges from filter #1? (b) What percent of the original intensity emerges from filter #2? (c) What percent of the original intensity emerges from filter #3? (d) If filter #2 has its transmission axis changed to 30.°, what % intensity now emerges from the 3rd filter?
A string is wound tightly around a fixed pulley whose radius is 5.0 cm. As the string is pulled, the pulley rotates without slipping. What is the angular speed of the pulley when the string has a linear speed of 5.0 m/s?
A) 100 rad/s B) 50 rad/s C) 25 rad/s D) 20 rad/s E) 10 rad/s
The strong nuclear force is
a. strongly repulsive for distances less than 10^-14 m and strongly attractive for larger distances. b. zero for distances less than 10-14 m and strongly attractive for larger distances. c. strongly attractive for distances less than 10^-14 m and zero for larger distances. d. strongly attractive for distances less than 10^-14 m and repulsive for larger distances.