Suppose two loaded train cars are moving toward one another, the first having a mass of 1.50 \times 10^5\, \mathrm{kg}1.50×10 5 kg and a velocity of (0.11 \, \mathrm{m/s})\, \hat{i}(0.11m/s) i ^ , and the second having a mass of 1.10 \times 10^5\, \mathrm{kg}1.10×10 5 kg and a velocity of (-0.21 \, \mathrm{m/s})\, \hat{i}(−0.21m/s) i ^ . what is their final velocity?

During takeoff, the sound intensity level of a jet engine is 170db at a distance of 34 m. what's the sound intensity level at a distance of 1.0 km?

(2) (a) you have a simple circuit that consists of only a battery (δvbat=1.5v) and two resistors with resistance r1=10ω and r2=5ω, connected in series with each other. what is the current running through the battery? (b) you re-arrange your circuit so now r2 is attached in parallel to r1 rather than in series. what is the current running through the battery? (c) you add an additional resistor r3=7ω on the same branch as r2. what is the current running through the battery? (d) what is the power dissipated in r3?

Which best describes the first law of thermodynamics as compared to the second law of thermodynamics? a. the first law describes how thermal energy is conserved but not the direction it moves. b. the first law describes the direction thermal energy moves but not how it is conserved. c. the first law describes how thermal energy can be created but not how it can be destroyed. d. the first law describes how thermal energy can be destroyed but not how it can be created.