When a loose brick is resting on a wall, it has energy. When the brick is pushed off the wall and is falling down, the amount of
2 answers:
The complete sentence is as follows:
When a loose brick is resting on a wall, it has potential energy. When the brick is pushed off the wall and is falling down, the amount of potential energy is decreasing while the amount of kinetic energy is increasing.
Explanation:
- Potential energy is the energy related to the position of an object: in particular, gravitational potential energy is given by
where m is the mass of the object, g is the gravitational acceleration, and h is the height of the object above the ground.
- Kinetic energy is the energy related to the motion of an object, and it is given by
where m is the mass and v the speed of the object.
In the example, we see that:
- at the beginning, the brick is at rest on the wall, so it only has potential energy due to its height above the ground (while the kinetic energy is zero, since it is at rest, so speed v is zero)
- as it falls down, the potential energy decreases, because the height h decreases, while the kinetic energy increases, because the speed of the object increases as it falls down.
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Answer:
a)
b)
c)
d)
Explanation:
From the question we are told that:
Population percentage
Sample size
Let x =customers ask for water
Let y =customers dose not ask for water with their meal
Generally the equation for y is mathematically given by
Generally the equation for pmf p(x) is mathematically given by
a)
Generally the probability that exactly 6 ask for water is mathematically given by
b)
Generally the probability that less than 9 ask for water with meal is mathematically given by
c)
Generally the probability that at least 3 ask for water with meal is mathematically given by
d)
Generally the mean and standard deviation of sample size is mathematically given by
Mean
Standard deviation
Forward thrust has positive values and reverse thrust has negative values.
Thrust is a sudden push or pull in a certain direction.
a)
Flight speed u = 150 km/h
1 km/h = km/s
therefore, 150 km/h = 41.67 km / s
The thrust force represents the horizontal or x-component of momentum equation:
T = 50 * (150 - 41.67)
T = 5416.67 N
Therefore, the value of forward thrust is 5416.67 N.
b)
Now the exhaust velocity is now vertical due to reverse thrust application, then it has a zero horizontal component,
thus thrust equation is:
T = 50 * (0 - 41.67)
T = -2083.5 N
Therefore, the thrust force T is -2083.5 N in the reverse direction.
c)
Now the exhaust velocity and flight velocity is zero, then it has a zero horizontal component, thus thrust is also zero because
T = 0
Therefore, there is no difference in two velocities in x direction.
The given question is incomplete, the complete question is,
"The idling engines of a landing turbojet produce forward thrust when operating in a normal manner, but they can produce reverse thrust if the jet is properly deflected. Suppose that while the aircraft rolls down the runway at 150 km/h the idling engine consumes air at 50 kg/s and produces an exhaust velocity of 150 m/s.
a. What is the forward thrust of this engine?
b. What are the magnitude and direction (i.e., forward or reverse) if the exhaust is deflected 90 degree without affecting the mass flow?
c. What are the magnitude and direction of the thrust (forward or reverse) after the plane has come to a stop, with 90 degree exhaust deflection and an airflow of 40 kg/s?"
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