If the cold temperature reservoir of a Carnot engine is held at a constant 318 K , what temperature should the hot reservoir be kept at so that the engine efficiency is 0.67

What is hidden during a lunar eclipse? isn't the moon hidden?

Truck traveling west on the highway experiences an acceleration to the east. what could be the cause of this acceleration

Which of the following is a true statement about the acceleration ~a of the pendulum bob ~a is equal to the acceleration due to gravity. ~a is perpendicular to the bob’s trajectory. ~a is equal to the instantaneous rate of change in velocity. ~a is tangent to the bob’s trajectory.