{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

exam1-solutions

exam1-solutions - Version 010 exam1 bohm(59970 This...

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

Version 010 – exam1 – bohm – (59970) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points You and your friend throw balloons filled with water from the roof of a several story apart- ment house. You simply drop a balloon from rest. A second balloon is thrown downward by your friend 3 . 3 s later with an initial speed of 64 . 68 m / s. They hit the ground simultane- ously. The acceleration of gravity is 9 . 8 m / s 2 . You can neglect air resistance. How high is the apartment house? 1. 68.9062 2. 159.201 3. 167.69 4. 53.361 5. 127.449 6. 80.3723 7. 44.1 8. 74.529 9. 142.884 10. 120.062 Correct answer: 120 . 062 m. Explanation: For balloon 1: y 1 = 1 2 g t 2 1 For balloon 2: y 2 = v 0 t 2 + g t 2 2 2 Balloon 2 is thrown Δ t seconds after balloon 1 and they hit the ground at the same time, so: t 1 = t 2 + Δ t Since the height of the house is the same for both of the balloons, y 1 = y 2 g t 2 1 2 = v 0 ( t 1 - Δ t ) + g 2 ( t 1 - Δ t ) 2 ( v 0 - g Δ t ) t 1 = v 0 Δ t - g 2 Δ t 2 t 1 = v 0 Δ t - g 2 Δ t 2 v 0 - g Δ t = Δ t 2 + v 0 v 0 - g Δ t Δ t 2 For Δ t = 2 s t 1 = 1 + v 0 v 0 - 2 g For v 0 = 30 m/s, Δ t = 2 s t 1 = 4 . 95 s From the above, once t 1 is known, the height of the house is given simply by y = g t 2 1 2 For t 1 = 4 . 95 s, y = 120 . 062 m 002 10.0 points Three vectors vector A , vector B , and vector C have the following x and y components: A x = 7 . 9, A y = - 6 . 3; B x = - 3 . 8, B y = 4 . 5; C x = 2 . 7, C y = 5 . 7. What is the magnitude of vector A + vector B + vector C ? 1. 8.5235 2. 8.27345 3. 2.33452 4. 3.80132 5. 9.45569 6. 7.83901 7. 2.06155 8. 3.67967 9. 10.5385 10. 5.59017 Correct answer: 7 . 83901. Explanation: Given : vector A = (7 . 9 , - 6 . 3) , vector B = ( - 3 . 8 , 4 . 5) , and vector C = (2 . 7 , 5 . 7) .

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

View Full Document
Version 010 – exam1 – bohm – (59970) 2 Let vector D = vector A + vector B + vector C . The x component o f vector D is D x = A x + B x + C x = 7 . 9+( - 3 . 8)+2 . 7 = 6 . 8 and the y component of vector D is D y = A y + B y + C y = - 6 . 3 + 4 . 5 + 5 . 7 = 3 . 9 . Thus the magnitude of vector A + vector B + vector C is given by D = radicalBig D 2 x + D 2 y = radicalbig 6 . 8 2 + 3 . 9 2 = 7 . 83901 . 003 10.0 points A car travels along a straight stretch of road.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 6

exam1-solutions - Version 010 exam1 bohm(59970 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online