A 25-mm-diameter uniform steel shaft is 600 mm long between bearings. (7-33) (9 Pts) A. Find the lowest critical speed of the sh
aft. B. If the goal is to double the critical speed, find the new diameter. C. A half-size model of the original shaft has what critical speed?
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The tennis ball lands at a point 40.4 m from the base of the building.
The tennis ball is projected with a horizontal velocity <em>u</em> from a window, which is at a height <em>y</em> from the ground. The ball lands at a distance <em>x</em> from the base of the building. Let the ball take a time <em>t</em> to reach the ground. In the time <em>t</em> ,the ball falls a vertical distance <em>y</em> and also travel a horizontal distance <em>x</em>.
The initial vertical velocity of the ball is zero, since the ball is projected in the horizontal direction. The ball falls down under the action of gravitational force.
Thus, use the equation of motion,
rewrite the expression for <em>t</em> and calculate the value of <em>t</em> using 9.81 m/s²for <em>g</em> and 500 m for <em>y</em>.
The horizontal distance <em>x</em> is traveled using the constant velocity <em>u </em>since no force acts on the ball in the horizontal direction.
Therefore,
Substitute 4 m/s for <em>u</em> and 10.096 s for <em>t</em>
Thus, the ball lands at a point 40.4 m from the base of the building.