(((QUESTION 1))) A person opens a door by applying a 17-N force perpendicular to

Question

(((QUESTION 1)))

A person opens a door by applying a 17-N force perpendicular to it at a distance 0.90m from the hinges. The door is pushed wide open (to 120 ? ) in 2.2s .

Part A

How much work was done?

Express your answer using two significant figures.

Part B

What was the average power delivered?

Express your answer using two significant figures.

(((QUESTION 2)))

The kinetic energy of a rotating body is generally written as K=12I?2, where I is the moment of inertia (also known as rotational inertia) of the body.

Part A

Find the moment of inertia of the particle described in the problem introduction with respect to the axis about which it is rotating. Assume ? = 11.0rad/s .

Express your answer numerically.

Explanation / Answer

Question 1)

Part A)

W = Torque(Angular Distance)

Angular distance... Convert 120o to radians

x/120 = pi/180

x = 2.09 rad

W = (17)(.9)(2.09)

W = 32.0 J

Part B)

P = W/t = 32/2.2

P = 14.6 W

Question 2

Part A)

I is just mr2

So...I = (20)(.75)2

I = 11.25 kgm2

(And, by the way, that would give you a KE of (.5)(11.25)(11)2 = 680.6 Joules)

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