A 6 kg mass is acted on by a net force shown in the graph above. a) if the object started
from rest, what is its velocity after it has moved 10 m? b) If the object in initially was moving
at 5 m/s in the direction of the net force, what was its speed after it had moved a distance of
6 m?
Answers
Answer:
What happens to the work done on a system? Energy is transferred into the system, but in what form? Does it remain in the system or move on? The answers depend on the situation. For example, if the lawn mower in Figure 1a is pushed just hard enough to keep it going at a constant speed, then energy put into the mower by the person is removed continuously by friction, and eventually leaves the system in the form of heat transfer. In contrast, work done on the briefcase by the person carrying it up stairs in Figure 1d is stored in the briefcase-Earth system and can be recovered at any time, as shown in Figure 1e. In fact, the building of the pyramids in ancient Egypt is an example of storing energy in a system by doing work on the system. Some of the energy imparted to the stone blocks in lifting them during construction of the pyramids remains in the stone-Earth system and has the potential to do work.