{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# hw6 - khounvivongsy(sk27799 – Homework 6 – Weathers...

This preview shows pages 1–2. Sign up to view the full content.

khounvivongsy (sk27799) – Homework 6 – Weathers – (17104) 1 This print-out should have 10 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 travels due east with a horizontal speed of 52 . 3 km / h. Rain is falling vertically with respect to Earth. The traces of the rain on the side windows of the car make an angle of 69 . 6 with the vertical. Find the magnitude of the velocity of the rain with respect to the car. Correct answer: 55 . 7996 km / h. Explanation: Taking down and west be positive, let v ce = velocity of car relative to Earth, v rc = velocity of rain relative to car, and v re = velocity of rain relative to Earth. Given : v ce = 52 . 3 km / h and θ = 69 . 6 . The car is moving out from under the rain, so the rain streaks are westward toward the rear bumper. v rc 52 . 3 km / h v re 69 . 6 Note: Figure is not drawn to scale sin θ = v ce v rc v rc = v ce sin θ = 52 . 3 km / h sin 69 . 6 = 55 . 7996 km / h at 69 . 6 west of vertical. 002 (part 2 of 2) 10.0 points Find the magnitude of the rain’s velocity with respect to Earth. Correct answer: 19 . 4502 km / h. Explanation: cos θ = v re v rc v re = v rc cos θ = (55 . 7996 km / h) cos 69 . 6 = 19 . 4502 km / h . 003 10.0 points A boat moves through the water of a river at 12 m / s relative to the water, regardless of the boat’s direction. If the current is flowing at 9 . 13 m / s, how long does it take the boat to complete a trip consisting of a 475 m displacement down- stream followed by a 197 m displacement up- stream? Correct answer: 91 . 121 s. Explanation: Let v b be the velocity of the boat relative to the water, and v w the velocity of water relative to the shore. Take downstream as the positive direction. For the downstream trip, the current is speeding him up, so the velocity of the boat relative to the shore is v d = v b + v w and the time is t d = x d v d = x d v b + v w For the upstream trip, the current is slowing him down, so the velocity of the boat relative to the shore is v u = v b - v w and the time is t u = x u v u = x u v b - v w The time for the entire trip is thus t = t d + t u = x d v b + v w + x u

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

View Full Document
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