If a star is 10 light-years away from us and it explodes today, when will we know that it exploded?
today
10 years from today
10 parsecs from today

Matt is driving down 7th street. he drives 150 meters in 18 seconds. assuming he does not speed up or slow down, what is his speed?

2kg of refrigerant 134a undergoes a polytropic process in a piston-cylinder assembly from an initial state of saturated vapor at 2 bar to a final state of 12 bar, 80 degree c. a)determine the work for the process in kj. b)sketch the process on a p-v diagram.

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?