There is still air inside of a house, which is pushing the roof upwards, so the forces are equal and the roof is not crushed.
The force must be applied for motor to keep the package moving is 50 N.
<h3>What is force?</h3>
Force is the action of push or pull the object in order to make it move or stop.
Power is related to force and velocity as
P = F x v
150 W = F x 3 m/s
F =50 N
Thus, the force must be applied for motor to keep the package moving is 50 N.
Learn more about force.
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Answer:
If the rifle is held loosely away from the shoulder, the recoil velocity will be of -8.5 m/s, and the kinetic energy the rifle gains will be 81.28 J.
Explanation:
By momentum conservation, <em>and given the bullit and the recoil are in a straight line</em>, the momentum analysis will be <em>unidimentional</em>. As the initial momentum is equal to zero (the masses are at rest), we have that the final momentum equals zero, so

now we clear
and use the given data to get that

<em>But we have to keep in mind that the bullit accelerate from rest to a speed of 425 m/s</em>, then <u>if the rifle were against the shoulder, the recoil velocity would be a fraction of the result obtained</u>, but, as the gun is a few centimeters away from the shoulder, it is assumed that the bullit get to its final velocity, so the kick of the gun, gets to its final velocity
too.
Finally, using
we calculate the kinetic energy as
