Which of the following situations results in zero work done? An applied force is parallel to the displacement on an object.

An applied force is anti-parallel (in the opposite direction) to the displacement on an object.

An applied force is perpendicular to the displacement of an object. An applied force is at some angle less than 90 degrees to the displacement of the object.

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

What happens to the light rays when they hit the specimen?

1point) a skydiver weighing 130 lb (including equipment) falls vertically downward from an altitude of 14,000 ft and opens the parachute after 20 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.85|v|0.85|v| when the parachute is closed and is of magnitude 17|v|17|v| when the parachute is open, where the velocity vv is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. find the speed of the skydiver when the parachute opens. speed is 150.6121788 ft/s find the skydiver's height when the parachute opens. height is 2338.98591 ft find the limiting velocity vlvl after the parachute opens. (think about whether this should be positive or negative.) vl=vl= 7.647 ft/s