HW-01-solutions

HW-01-solutions - kuruvila(lk5992 – HW-01 – gokce...

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Unformatted text preview: kuruvila (lk5992) – HW-01 – gokce – (P111S11) 1 This print-out should have 16 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Consider the expression 2 π radicalBigg ℓ g , where ℓ is length and g is gravitational acceleration in units of length divided by time squared. Evaluate its units. 1. m 2. m s 3. parenleftBig s m parenrightBig 2 4. m 2 5. s 2 6. s m 7. parenleftBig m s parenrightBig 2 8. s correct Explanation: [ ℓ ] = m and [ g ] = m s 2 . 2 and π are constants, so radicalBigg [ ℓ ] [ g ] = radicalbigg m ÷ m s 2 = radicalbigg m · s 2 m = √ s 2 = s . 002 10.0 points Rain drops fall on a tile surface at a density of 4584 drops / ft 2 . There are 11 tiles / ft 2 . How many drops fall on each tile? Correct answer: 416 . 727 drops / tile. Explanation: Let : ρ = 4584 drops / ft 2 and n = 11 tiles / ft 2 . Applying dimensional analysis, R = ρ n = 4584 drops / ft 2 11 tiles / ft 2 = 416 . 727 drops / tile . 003 10.0 points An electron travels 2 . 13 m in 6 . 4 μ s (microsec- onds). What is its speed if 1 inch = 0.0254 m? Correct answer: 7 . 86171 × 10 8 in / min. Explanation: Let : L = 2 . 13 m and t = 6 . 4 μ s = 6 . 4 × 10 − 6 s . The speed is v = L t = 2 . 13 m 6 . 4 × 10 − 6 s · 100 cm 1 m · 1 in 2 . 54 cm · 60 s 1 min = 7 . 86171 × 10 8 in / min . 004 10.0 points A high fountain of water is located at the center of a circular pool as in the figure. A student walks around the pool and estimates its circumference to be 209 m. Next, the student stands at the edge of the pool and uses a protractor to gauge the angle of elevation of the top of the fountain to be 61 . 6 ◦ . How high is the fountain? Correct answer: 61 . 5194 m. Explanation: kuruvila (lk5992) – HW-01 – gokce – (P111S11) 2 Let : C = 209 m and θ = 61 . 6 ◦ . R h θ The circumference of the pool is C = 2 π R , so its radius is R = C 2 π = 209 m 2 π = 33 . 2634 m ....
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This note was uploaded on 02/12/2011 for the course PHYS 111 taught by Professor Moro during the Spring '08 term at NJIT.

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HW-01-solutions - kuruvila(lk5992 – HW-01 – gokce...

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