Author Question: Two simple pendulums of equal length l = 0.45 m are suspended from the same point. The pendulum bobs ... (Read 84 times)

bobbysung · **on:** Jul 29, 2018

Two simple pendulums of equal length l = 0.45 m are suspended from the same point. The pendulum bobs are small solid steel spheres. The first bob is drawn back to make a 35 angle with the vertical, while the other one is left hanging at rest.

If the first bob has a mass of 0.25 kg and the second has a mass of how high will the second bob rise above its initial position when struck elastically by the first bob after it is released?
A) 2.7 cm B) 3.3 cm C) 4.4 cm D) 3.9 cm

Question 2

How do we know what Earth's temperature was many years before thermometers existed?

A) From computer calculations that start from the conditions (the atmosphere and sea level, primarily) of earlier times and then calculate the resulting temperature.
B) From laboratory experiments that reconstruct the conditions (the atmosphere and sea level, primarily) of earlier times and then measure the resulting temperature.
C) From such indirect methods as tree rings (the thickness and density of a ring is dependent on the temperature at the time of growth) and annual layers of ice in ice cores.
D) From historical information about the climate recorded by Vikings and other travelers during the ice ages.
E) From computer calculations that work backward from the present time to calculate the temperature at earlier times.