Which two properties characterize an air mass?
2 answers:
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Answer:
The net force is zero
Explanation:
When an object is falling, there are two forces acting on it:
- The force of gravity, which is equal to the weight of the object, which pushes the object downwards
- The air resistance, which acts against the motion of the object, so it pulls upward
While the magnitude of the force of gravity is constant, the magnitude of the air resistance increases as the velocity of the falling object increases: at some point of the motion, the air resistance becomes equal in magnitude to the force of gravity. At this point, the net force on the object becomes zero, and according to Newton's second law, the acceleration of the object becomes also zero:
But zero acceleration means that the velocity of the object is now constant: this is known as terminal velocity.
Answer:
Vf = 210 [m/s]
Av = 105 [m/s]
y = 2205 [m]
Explanation:
To solve this problem we must use the following formula of kinematics.
where:
Vf = final velocity [m/s]
Vo = initial velocity = 0 (released from the rest)
g = gravity acceleration = 10 [m/s²]
t = time = 21 [s]
Vf = 0 + (10*21)
Vf = 210 [m/s]
Note: The positive sign for the gravity acceleration means that the object is falling in the same direction of the gravity acceleration (downwards)
The average speed is defined as the sum of the final speed plus the initial speed divided by two. (the initial velocity is zero)
Av = (210 + 0)/2
Av = 105 [m/s]
To calculate the distance we must use the following equation of kinematics
44100 = 20*y
y = 2205 [m]