physics_ch3homework

physics_ch3homework - Chapter 3 Homework 9. A physics book...

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Chapter 3 Homework 9. A physics book slides off a horizontal tabletop with a speed of 1.10 m/s. It strikes the floor in 0.350 s. Ignore air resistance. Find (a) the height of the tabletop above the floor - = + y y0 v0yt 12 ayt2 = . + - . . 0ms0 350 s 12 9 80ms20 350 s2 =- . 0 600 m [0.600 m above the floor] (b) the horizontal distance from the edge of the table to the point where the book strikes the floor - = + x x0 v0xt 12 axt2 = . . + . 1 10 ms0 350 s 12 0ms20 350 s2 = . 0 385 m (c) the horizontal and vertical components of the book's velocity, and the magnitude and direction of its velocity, just before the book reaches the floor. = + vx v0x axt = . + ( . ) 1 10ms 0ms2 0 350 s = . 1 10 ms = + vy v0y ayt = + - . ( . ) 0ms 9 80ms2 0 350 s =- . 3 43 ms = + v vx2 vy2 = . + - . 1 10ms2 3 43ms2 = . 3 60ms = - + ° α tan 1vyvx 360 = - - . . tan 1 3 43ms1 10ms + ° 360 = . ° 287 8 Page | 1 2.2.11

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10. A military helicopter on a training mission is flying horizontally at a speed of 60.0 m/s and accidentally drops a bomb at an elevation of 300 m. You can ignore air resistance. (a) How much time is required for the bomb to reach the earth? - = + y y0 v0yt 12 ayt2 = + . 300 m 0mst 12 9 80mst2 = . t 7 82 s (b) How far does it travel horizontally while falling? - = + x x0 v0xt 12 axt2 = . . + . 60 0 ms7 82 s 12 0ms27 82 s2 = 469 m (c) Find the horizontal and vertical components of its velocity just before it strikes the earth. = + vx v0x axt = . + ( . ) 60 0 ms 0ms2 7 82 s = . 60 0 ms = + vy v0y ayt = + . ( . ) 0ms 9 80ms2 7 82 s = . 76 7 ms (e) If the velocity of the helicopter remains constant, where is the helicopter when the bomb hits the ground? 300 m directly above the bomb at impact (f) What’s the magnitude and direction of the velocity when the bomb hits the ground? = + v vx2 vy2 = . + . 60 0 ms2 76 7 ms2 = . 97 4 ms = - α tan 1vyvx = - . . tan 176 7 ms60 0 ms = . ° 60 0 11. Two crickets, Chirpy and Milada, jump from the top of a vertical cliff. Chirpy just drops and reaches the ground in 3.50 s, while Milada jumps horizontally with an initial speed of 95.0 cm/s. Page | 2 2.2.11
How far from the base of the cliff will Milada hit the ground? - = + x x0 v0xt 12 axt2 = . . + . 0 950ms3 50 s 12 0ms23 50 s2 = . 3 325 m 13. A car comes to a bridge during a storm and finds the bridge washed out. The driver must get to the other side, so he decides to try leaping it with his car. The side of the road the car is on is 21.3 m above the river, while the opposite side is a mere 1.8 m above the river. The river itself is a raging torrent 61.0 m wide. (a) How fast should the car be traveling at the time it leaves the road in order just to clear the river and land safely on the opposite side? -

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This note was uploaded on 03/26/2011 for the course PHY 210 taught by Professor Mcdemus during the Spring '11 term at Lehigh Carbon CC.

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physics_ch3homework - Chapter 3 Homework 9. A physics book...

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