Distance is 33 km, displacement is 3 km east
Explanation:
- Distance is a scalar quantity equal to the total length of the path covered by an object during its motion, regardless of its direction.
- Displacement is a vector connecting the starting position of motion of an object to its final position. It is a vector quantity, therefore it has both magnitude and direction.
In this problem, the motion of the person is:
12 km north
6 km east
12 km south
3 km west
Therefore, the distance is:

The displacement instead can be calculated by comparing the final position with the initial position. We notice that:
- the person goes 12 km north and 12 km south, so he didn't move in the north-direction
- The person goes 6 km east and 3 km west, so his final position is 3 km east
Therefore, the displacement is 3 km east.
Learn more about distance and displacement:
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In short, when light illuminates a piece of metal, the light kicks off electrons from the metal’s surface and these electrons can be detected as a change in the electric charge of the metal or as an electric current. Hence the name: photo for light and electric for the current. The explanation behind this simple phenomenon opened the door to revolutionary modern physics concepts regarding the composition of light, quantum mechanics, and what is now referred to as the “wave-particle duality” of nature. The wave-particle duality of nature is perhaps one of the greatest mysteries of our universe and a very interesting philosophical subject! Your goal in this lab is to reproduce the photoelectric effect for yourselves and to understand how it demonstrates the particle behavior of light.
Answer:
No work was done at all.
Explanation:
Work is only done when a force is exerted and it moves an object. However, when the man exerted his force on the car, the car did not move at all. Therefore, no work was done.
Answer:
28
Explanation:
There is a 28 day cycle of the moon phase as it rotates on earths axis.
Answer:
work output is always less than work input - the ratio is less than 1.
Explanation:
This principle comes from the fact that a machine or system cannot produce more work than is supplied to it, because this would violate the energy conservation law (work is a type of mechanical energy).
In theoretical machines called "ideal machines" the input work is the same as the output work, but these machines are only theoretical because in real applications there is always some type of energy loss, either in heat produced by a machine or processes for its operation, for this reason the output work is always less than the input work.
Regarding the ratio work output to work input:

because work input WI is always greater than work output WO.