In: Physics
While exploring a castle, Exena the Exterminator is spotted by a dragon who chases her down a hallway. Exena runs into a room and attempts to swing the heavy door shut before the dragon gets her. The door is initially perpendicular to the wall, so it must be turned through 90∘ to close. The door has a height of 3.00 m and a width of 1.15 m , and its weight is 720 N . You can ignore the friction at the hinges.
If Exena applies a force of 250 N at the edge of the door and perpendicular to it, how much time does it take her to close the door?
Use 9.80 m/s2 for the acceleration due to gravity.
The Door is turning by applying a perpendicular Force F at distance which is equal to the width of the door
Torque =Moment of Inertia * angular acceleration
Moment of interia of a rectangular plane about edge ,where w is the width
Given Weight of Door =720N ,so Mass M =W/g
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Since the door is initially at rest
initial angular velocity ,
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The Door needs to turn 90 degrees ,so
Use formula
ANSWER:
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