Experiments using "optical tweezers" measure the elasticity of individual dna molecules. for small enough changes in length, the elasticity has the same form as that of a spring. a dna molecule is anchored at one end, then a force of 1.5 nn (1.5×10−9n) pulls on the other end, causing the molecule to stretch by 5.0nm (5.0×10−9m). what is the spring constant of that dna molecule?

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

Acalorimeter uses the principle that thermal energy flows from hotter material to colder material until both reach the same

Simon is writing a story about an astronaut whose spacecraft has been boarded by space pirates. the astronaut has her lucky penny in her hand behind her back as the space pirates break into the control room. she has just locked the controls so that the ship is accelerating in the direction of the control room’s ceiling. simon wants the astronaut to use the penny to hit a button on the control panel to turn off the lights and escape. the button is located a short distance behind and below the astronaut’s hands. how should simon use the theory of relativity to describe what the astronaut must do in order to hit the button?