A ball falls to the ground from height h and bounces to height h'. Momentum is conserved in the ball-earth system
a. no matter what height h' it reaches.
b. only if h' < h.
c. only if h' = h.
d. only if h' > h.
e. only if h' ³ h.
A
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Which of the following is an example of a scientific model?
a. celestial sphere b. connected balls and rods representing chemical bonds of a DNA molecule c. topographical map d. All of the other choices are correct.
Again consider two twin sisters, Gwen and Jackie, who are both 20 years old in the year 2020. This time, assume that Jackie makes the round-trip to Vega, which is 25 light-years away, at an average speed of 0.9999c
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A telescope is used to view two small lights separated by 2.0 cm at a distance of 500 m. What minimum objective lens diameter is needed to just resolve these objects if their wavelength is 656 nm?
a. 2.0 cm b. 1.0 cm c. 1.2 cm d. 2.4 cm
A stone is thrown at an angle of 30° above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 4.8 s. What is the height of the cliff? (g = 9.8 m/s2 and air resistance is negligible)
a. 140 m b. 110 m c. 84 m d. 29 m