Sunspots increase and decrease periodically over a 15 year time span.
a. true
b. false
False
Regular increase and decrease of sunspots and other solar activity, which are thought to be physically related. Sunspots go through one cycle of activity in approximately 11 years. The Sun's magnetic polarity reverses between every cycle.
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A box slides down a frictionless incline, and a hoop rolls down another incline. Both inclines have the same height, and both the box and the hoop have the same mass. If both objects start from rest, upon reaching the bottom of the incline which one will have the greater kinetic energy and which one will have the greater speed?
a. The box will have both the greater kinetic energy and the greater speed. b. The hoop will have both the greater kinetic energy and the greater speed. c. Both will have the same kinetic energy, but the hoop will have the greater speed. d. Both will have the same kinetic energy, but the box will have the greater speed.
What is the mass of a ball moving at 3 m/s with a momentum of 48 kg?m/s?
A) 4 kg B) 12 kg C) 16 kg D) 144 kg E) none of these
An isotope is simply an atom that
A) is electrically charged. B) has different numbers of neutrons for the same element. C) both of these D) neither of these
The two men compete in a tug of war. Both pull equally and the scale reads 800 newtons. Each man must pull with a force of
1) 400 N. 2) 800 N. 3) 0 N. Consider action and reaction forces in this case: If action is the man on the left pulling on the rope, then the reaction force is 4) the rope pulling on the man on the left. 5) the rope pulling on the man on the right. 6) the man on the right pulling on the rope.