Calmweek15HW15solutions

Calmweek15HW15solutions - HOMEWORK: Week 15 Chapter 15 -...

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HOMEWORK: Week 15 – Chapter 15 - SOLUTIONS (15.56) On a vacation flight, you look out the window of the jet and wonder about the forces exerted on the window. Suppose the air outside the window moves with a speed of approximately 150 m/s shortly after takeoff, and that the air inside the plane is at atmospheric pressure. (a) Find the pressure difference between the inside and outside of the window. (b) If the window is 25 cm by 42 cm, find the force exerted on the window by air pressure. SOLUTION (a) 22 in in out out 11 Pv P v ρρ += + in out out in 2 2 3 1 () 2 1k g m 1.29 150 0 2s m 15 kPa PP P vv ρ ∆= − =− ⎡⎤ ⎛⎞ =⎢ ⎜⎟ ⎝⎠ ⎢⎥ ⎣⎦ = (b) 3 (14.5 10 Pa (0.25 m)(0.42 m) 1.52 kN FP A ∆= ∆ = × = (15.8) A 67-kg person sits on a 3.5-kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.5 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is evenly distributed. SOLUTION ( ) 2 m s 5 2 0.015 m 2 (67 kg 3.5 kg) 9.81 9.8 10 Pa 4 Fm g P AA π + == = = × (15.16) In the hydraulic system shown in Figure 15–28, the piston on the left has a diameter of 4.5 cm and a mass of 1.7 kg. The piston on the right has a diameter of 12

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This note was uploaded on 07/02/2011 for the course PHYS 201 taught by Professor Woodahl during the Fall '09 term at Indiana.

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Calmweek15HW15solutions - HOMEWORK: Week 15 Chapter 15 -...

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