..ooo T-Mobile 8:40 PM 65% webassign.net 7. 11/12 points| Previous Answers My No

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..ooo T-Mobile 8:40 PM 65% webassign.net 7. 11/12 points| Previous Answers My Notes EXAMPLE 4.4 That's Quite an Arm! A stone is thrown from the top of a building upward at an angle of 26.0° to the horizontal with an initial speed of 23.4 m/s as shown in the figure. The height of the building is 45.0 m (A) How long does it take the stone to reach the ground? (B) What is the speed of the stone just before it strikes the ground? SOLVE IT Conceptualize Study the figure, in which we have indicated the trajectory and various parameters of the motion of the stone (0, 0) Categorize We categorize this problem as a projectile motion problem. The stone is modeled as a particle under constant acceleration in the y direction and a particle under constant velocity in the r direction. 45.0 m Analyze We have the information .r.-y, = 0, 45.0 m, ayg, and v, -23.4 m/s (the numerical value of y is negative because we have chosen the top of the building as the origin). y=-15.0m : A stone is thrown from the top of a building. (A) How long does it take the stone to reach the ground? Find the initial xand y components of the stone's velocity: v,, = v, cos ' = (23.4 m/s) cos 26.0° = | 21 m/s Yv = v, sin 0, = (23.4 m/s) sin 26.0° m/s 10.3 Express the vertical position of the stone from the vertical component of Equation 4.9: Substitute numerical values: -45.0 m = (10.258 m/s)I + ½(-9.80 m/s2)I2 Solve the quadratic equation for r: (B) What is the speed of the stone just before it strikes the ground? Use the y component of Equation 4.8 with t = 4.253 s to obtain the y component of the

Explanation / Answer

Horizonal component of the velocity must be 1.5 time, because horizontal velocity does not change only vertical velocity changes.

Hence horizontal component of the velocity must be multiplied by factor 1.5

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