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092810physhw

# 092810physhw - does it take to hit the ground D = V i t...

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David Kim Physics Period 9 09/27/10 Physics Hw. Pg. 85, # 1-7 A ball rolls down a hill with a constant acceleration of 2.0 m/s 2 . The ball starts at rest and travels for 4.0 s before it stops. 1. How far did the ball travel before it stopped? D = V i t + ½at 2 D = (0 m/s)(4.0 s) + ½(2.0m/s 2 )(4.0 s) 2 D = ½(2.0m/s 2 )(16 s 2 ) (C) D = 16 m 2. What was the ball’s velocity just before it stopped? V f = V i + at V f = (0 m/s) + (2.0m/s 2 )(4.0 s) (B) V f = 8.0 m/s 3. A driver of a car enters a new 110-km/h speed zone on the highway. The driver begins to accelerate immediately and reaches 110 km/h after driving 500 m. If the original speed was 80 km/h, what was the driver’s rate of acceleration? V f 2 = V i 2 + 2ad (110 km/h) 2 = (80 km/h) 2 + 2a(.5 km) 5700 km/h 2 = a 5700 km/h 2 (1000 m / 1 km) (1 h 2 / 12960000 s 2 ) (A) 0.44 m/s 2 4. A flowerpot falls off the balcony of a penthouse suite 85 m above the street. How long

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Unformatted text preview: does it take to hit the ground? D = V i t + ½at 2 85 m = (0 m/s)(t) + ½(9.8m/s 2 )t 2 (A) 4.2 s 5. A rock climber’s show loosens a rock, and her climbing buddy at the bottom of the cliff notices that the rock takes 3.20 s to fall to the ground. How high up the cliff is the rock climber? D = V i t + ½at 2 D = (0 m/s)(3.20 s) + ½(9.8m/s 2 )(3.20 s) 2 (C) 50.0 m 6. A car traveling at 91.0 km/h approaches the turnoff for a restaurant 30.0 m ahead. If the driver slams on the brakes with an acceleration of -6.40 m/s 2 , what will be her stopping distance? V f 2 = V i 2 + 2ad 2 = (91.0 km/h) 2 + 2(-6.40 m/s 2 )d-(25.3 m/s) 2 = (-12.8 m/s 2 )d (C) 50.0 m 7. What is the correct formula manipulation to find acceleration when using the equation V f 2 = V i 2 + 2ad? (D) (V f 2- V i 2 ) / 2d...
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092810physhw - does it take to hit the ground D = V i t...

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