# h8 - hernandez(ejh742 homework 08 Turner(58120 This...

This preview shows pages 1–3. Sign up to view the full content.

hernandez (ejh742) – homework 08 – Turner – (58120) 1 This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 29 . 5 below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration of 6 . 08 m / s 2 and travels 47 . 9 m to the edge of the cliff. The cliff is 43 . 1 m above the ocean. The acceleration of gravity is 9 . 8 m / s 2 . Find the car’s position relative to the base of the cliff when the car lands in the ocean. Correct answer: 41 . 8314 m. Explanation: Given : a = 6 . 08 m / s 2 , l = 47 . 9 m , h = 43 . 1 m , and θ = 29 . 5 . The speed of the car when it reaches the edge of the cliff is given by v 2 = v 2 i + 2 a l = 2 a l since v i = 0 m / s, so v = 2 a ℓ = radicalBig 2 (6 . 08 m / s 2 ) (47 . 9 m) = 24 . 1343 m / s . Now, consider the projectile phase of the car’s motion. The initial vertical velocity is v iy = v sin θ = (24 . 1343 m / s) sin(29 . 5 ) = 11 . 8843 m / s . and the vertical velocity with which the car strikes the water is v 2 y = v 2 iy + 2 g h = v 2 sin 2 θ + 2 g h = (24 . 1343 m / s) 2 sin 2 29 . 5 + 2 ( 9 . 8 m / s 2 ) (43 . 1 m) = 985 . 997 m 2 / s 2 , so that v y = radicalBig 985 . 997 m 2 / s 2 = 31 . 4006 m / s . To find the time of flight, v y = v iy + g Δ t Δ t = v y - v iy g The initial horizontal velocity is v ix = v cos θ and the horizontal motion of the car during this time is x = v ix Δ t = ( v cos θ ) v y - v iy g = (24 . 1343 m / s) cos 29 . 5 × (31 . 4006 m / s) - (11 . 8843 m / s) (9 . 8 m / s 2 ) = 41 . 8314 m . 002 (part 2 of 2) 10.0 points Find the length of time the car is in the air. Correct answer: 1 . 99146 s. Explanation: Using the vertical motion, v y = v iy + g t t = v y - v iy g = (31 . 4006 m / s) - (11 . 8843 m / s) (9 . 8 m / s 2 ) = 1 . 99146 s . 003 10.0 points A soccer player kicks a rock horizontally off a 38 . 1 m high cliff into a pool of water.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
hernandez (ejh742) – homework 08 – Turner – (58120) 2 The acceleration of gravity is 9 . 8 m / s 2 .
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern