The carbon dating method discussed in the video is useful for determining the ages of living materials that are a few thousand or a few tens of thousands years old. K-40 decays into Ar-40 with a half life of 1.2 billion years, making it suitable for estimating the age of very old astronomical objects (for the simplicity of this problem, we assume that this is the only possible decay for K-40). Assume that when a particular rock formed, it had a decay rate of 0.061 decays/sec/g, and it now has a decay rate of 0.015 decays/sec/g. Using the estimation method in the video, which is the closest estimate for the age of this rock? a. 0.3 billion years
b. 0.6 billion years
c. 1.2 billion years
d. 2.4 billion years
e. 4.8 billion years

Arock is dropped from a cliff and reaches the ground in 2.70s. at the same time another rock is thrown horizontally from the same height with initial x velocity of 0.95 m/s. what distance will in x will the second rock cover?

Aroll in a paper machine is powered by a separately excited dc machine. operating point 1 (under load): the roll typically operates at 764 rpm and must provide 301 nm of torque to oppose the load of the paper. the armature voltage is 230v for this operating point operating point 2 (no load): when the load is removed the speed of the roll increases to 900 rpm (the field characteristics are unchanged) la ea dev m (a) calculate the maximum torque (units of nm) that the motor can supply with this applied voltage (b) calculate the value of the armature resistance, ra (in ohms) (c) at operating point 1 (loaded condition), the field current, i, and the total input power (armature field), are measured to be to be 10 a and 28,600 w respectively. use this information to calculate the value of the field resistance, rf (in ohms). (d) (d) at operating point 1 (loaded condition), calculate the motor efficiency. express your answer as a percent to at least 2 significant digits. (d) if the field voltage is reduced by 1/2, calculate the new stall torque (in nm) of the motor (f). if the field voltage is reduced by 1/2, calculate the new no-load speed (in rad/sec)

What happens in a global convection cell