Question

In: Physics

While exploring a castle, Exena the Exterminator is spotted by a dragon who chases her down...

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.

Expert Solution

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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genius_generous answered 8 months ago

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