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Rectilinear Motion A 75 kg man stands on a spring scale in an elevator. During the first 3 secs of motion from rest, the tension T in the hoisting cable is 8300N. Find the reading R of the scale in N during this interval and the upward velocity v of the elevator at the end of the 3secs. The total mass of the elevator, man, and scale is 750kg. Ans. 830 N & 3.77m/s 2. T = 8300 N 1+ 750(9.81)=7360 N R 75(9.81)= 736 N

On an airplane’s takeoff, the combined action of the air around the engines and wings of an airplane exerts an 8 000-N force on the plane, directed upward at an angle of 65.0° above the horizontal. The plane rises with constant velocity in the vertical direction while continuing to accelerate in the horizontal direction. (a) What is the weight of the plane? (b) What is its horizontal acceleration?

(a) Calculate the tension (in N) in a vertical strand of spiderweb if a spider of mass 7.00 x 105 kg hangs motionless on it. (Enter a number.) N (b) Calculate the tension (in N) in a horizontal strand of spiderweb if the same spider sits motionless in the middle of it much like the tightrope walker in the figure. 5.0° 5,0° T. TR T I Ta w The strand sags at an angle of 12.0° below the horizontal. (Enter a number.) N Compare this with the tension in the vertical strand (find their ratio). (Enter a number.) (tension in horizontal strand)/(tension in vertical strand) =