Answer: because the air currents move upwards so the hot air fills up the whole room. Similarly if the air conditioner is placed neer the ceiling because it gives cool air
Answer:
B) A stack of books is carried at waist level across a room
Explanation:
Work is defined as:
where
F is the force applied
d is the displacement of the object
is the angle between the direction of the force and of the displacement
From the formula, we see that the work done is zero when the force and the displacement are perpendicular to each other. Let's now analyze each situation:
A) A bookcase is slid across carpeting. --> work is done, because the force that pushes the bookcase is in the same direction of the displacement
B) A stack of books is carried at waist level across a room. --> no work is done, because the force to carry the book is vertical, while the displacement of the books is horizontal
C) A chair is lifted vertically with respect to the floor. --> work is done, because the force that lifts the chair is vertical, and the displacement is vertical as well
D) A table is dropped onto the ground. --> work is done, because the force of gravity (that makes the table falling down) is vertical and the displacement of the table is also vertical.
Velocity is speed plus the direction of the speed.
NaCl is a compound formed by a chemical reaction between Na (Sodium) and Cl (Chlorine). Sodium is an alkai metal in Group One of the Periodic Table, and it is very reactive. All alkai metals react violently with water and they are often found combined in nature because they are that reactive. Chlorine is a halogen in Group 17 of the Periodic Table and they are very reactive.
<h2>The different forces acting on the ball while its in air</h2>
Amy throws a softball through the air. Applied, drag and gravitational forces are acting on the ball while it’s in the air. The softball experiences force as a result of Amy’s throw. As the ball moves, it experiences from the air it passes through.
It also experiences a downward pull because earth has the property to attract everything which is on the earth towards it. The ball is moving in the air but earth applies force on the ball to get back on the ground. Hence, in this way, gravitational force applies.
There is also a drag force which results due to friction that is present in the air. It resist to move ball in the air and there will also be applied force which is given by a person who throws by applying force.
