Answer:
The girl is doing work on the ball because the energy in her muscles changed, even though the ball is not displaced.
Explanation:
The complete question is...
Which of these correctly describes whether a girl holding a ball in the same position is doing work on the ball?
-The girl is doing work on the ball because the energy of the ball changed, even though it is not displaced.
-The girl is doing work on the ball because the energy in her muscles changed, even though the ball is not displaced.
-The girl is doing no work on the ball because the ball is not displaced.
-The girl is doing no work on the ball because she is exerting a net force on the ball.
Holding up a ball costs energy, which is used to counter the work that would have otherwise be done on the ball by gravity. Although no physical distance is moved, we should consider the fact that by holding the ball, the girls hand exerts physical force to hold the ball in place. Also, there is a potential gravitational work on the ball due to gravity, but the force exerted by the girls hand does an equivalent of this gravito-potential work in order to counter it and hold the ball in place. All these activities eventually lead to a change in energy in her hand muscle to show that energy is expended.
Answer:
This law states that every particle attract every other particle in the universe with a force that is directly proportional to the product of their mass and inversely proportional to the square of the distance between the center
Explanation:
Mass = 40 g
edge of cube = 1.74 cm
volume of cube = s^3 = 1.74^3 = 1.74 * 1.74 * 1.74 = 5.268024cm cube
density = Mass/volume
= 40/5.268024
= 7.6 g/cm
<span>They would feel that the water is cold.
</span> The atmosphere is heated both by the Sun and by the Earth's surface. Water radiates heat differently than land, so the air temperature over the ocean is usually different than the air temperature over land. <span>
The difference in air temperature over land compared to over water causes convection currents in the atmosphere. How would a person at the beach experience these convection currents?
</span>They would feel that the water is cold.
NOT:
They would feel the heat of the Sun.
They would feel that the sand is hot.
<span>They would feel wind as the air moves.</span>