If a positive test charge is placed in an electric field, what is the direction of the force on the test charge?
1 answer:
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Answer: The weight of the air displaced by the balloon is less than the volume of the balloon.
Explanation:
A hot air balloon is a cloth wrap that contains several thousand cubic meters of air inside (a large volume of air). The burner heats the liquid propane to a gaseous state to generate a huge flame, which can reach more than 3 meters, thus heating the air mass inside the balloon. In this way,<u> its density is modified with respect to the air that surrounds it</u>, because the hot air is lighter than the outside air (less dense), causing the balloon to rise and float.
Now, if we know that the density of a body is directly proportional to its mass
and inversely proportional to its volume
:
We can deduce that <u>by increasing the volume of the body, its density will decrease.</u>
This is proof of <em><u>Archimedes' Principle</u></em>:
<em>A body totally or partially immersed in a fluid at rest, experiences a vertical upward thrust equal to the mass weight of the body volume that is displaced.</em>
In this case the fluid is the air outside. So, the warm air inside the balloon, being less dense, will weigh less than the outside air and therefore will receive an upward pushing force or thrust that will make the balloon ascend.
All the answers are:
a) The time that will it take to rise to the highest point is 3.06 seconds.
b) The ball will rise to a height of 45.87 meters.
c) The time at which the ball will have a velocity of 10 m/s upward is 2.04 seconds.
The time when the ball has 10 m/s downward is 1.02 seconds.
d) The displacement of the ball will be zero at 6.12 seconds.
e) The time when the magnitude of the ball's velocity is equal to half its velocity of projection is 1.53 seconds.
f) The ball's displacement is equal to half the maximum height to which it rises after 0.90 seconds.
g) In each moment (upward and downward) the magnitude of the acceleration is the value of g (9.81 m/s²) and is a vector in the negative y-direction.
Let's calculate the values for each case.
a) At the highest point, the final velocity is 0, so we can use the following equation.
(1)
Where:
- v(i) is the initial velocity
- v(f) is the final velocity
- g is the acceleration due to gravity (9.81 m/s²)
We know that v(i) = 30 m/s.
Solve it for t:
Hence, the time is 3.06 s.
b) At the highest point, the final velocity is 0, so we can use the following equation.
(2)
We know that the initial velocity is 30 m/s.
Solving it for h we have:
Then, the height is 45.87 m.
c) Using equation (1) we can find the time (t).
So, the time elapsed to get 10 m/s is:
We know the upward time is equal to the downward time. So the time from v=10 m/s to v=0 m/s will be.
This is the time when the ball has 10 m/s downward.
Therefore, the time upward is 2.04 s, and the time downward is 1.02 s.
d) It will be when the ball returns to the ground.
The displacement will be zero after 6.12 s.
e) Here we need to find the time when v(f) is 15 m/s
The time when the v(f) is 15 m/s is 1.53 s.
f) Here, we need to find t when h = 45.87/2 m = 22.94 m
We can use the next equation:
[tex]h=v_{i}t-0.5gt^{2}/tex]
[tex]22.94=30t-0.5*9.81*t^{2}/tex]
Solving this quadratic equation, t will be:
[tex]t=0.90\: s/tex]
Hence, the ball's displacement is equal to half the maximum h, at 0.90 s.
g) In each moment the magnitude of the acceleration is the value of g (9.81 m/s²) and is a vector in the negative y-direction.
Learn more about vertical motion here:
I hope it helps you!