Question 1
In a given frictionless displacement of a particle, its kinetic energy increases by 25 J while its potential energy decreases by 10 J. Determine the work of the nonconservative forces acting on the particle during this displacement.
◦
−15 J
◦
+35 J
◦
+15 J
◦
−35 J
◦
+55 J
Question 2
Jane and Jake are looking at what happens to body 1 of mass m and body 2 of mass 2m, initially at rest, when equal forces are applied separately to the two bodies. Jake says that equal forces applied for equal times do equal amounts of work on the two bodies. Jane says that the two forces do equal amounts of work only if the two bodies move equal distances in the direction of the forces. Which one, if either, is correct?
◦
Jake, because the speed of body 1 is half the speed of body 2, but m1v1 = m2v2.
◦
Jane, because work does not depend on mass, only on force times distance.
◦
Jake, because all bodies travel equal distances when equal forces are applied for equal times.
◦
Jane, because it takes the same time for all bodies to travel equal distances when equal forces are involved.
◦
Neither, because we can't compare the amounts of work done on bodies of different mass.
Homunculus maps of human body parts along the cerebral cortex.
Countercurrent heat exchange in dolphin flippers promotes conservation of body heat.
The spinal cord protrudes from the body.
Calipers being used to measure body fat on the triceps of a patient.
Air-Mass Source Regions for North America
Acoelomate body plan of a flatworm