1. A certain car is capable of accelerating at a rate of+0.70m/s 2 . How long do
ID: 1752363 • Letter: 1
Question
1. A certain car is capable of accelerating at a rate of+0.70m/s2. How long does it take for this car to go from aspeed of 25 mi/h to a speed of85 mi/h? 2.A certain freely falling object requires 1.05 s to travel the last 29.5 m before it hits the ground. From what heightabove the ground did it fall? 1. A certain car is capable of accelerating at a rate of+0.70m/s2. How long does it take for this car to go from aspeed of 25 mi/h to a speed of85 mi/h? 2.A certain freely falling object requires 1.05 s to travel the last 29.5 m before it hits the ground. From what heightabove the ground did it fall?Explanation / Answer
a = v/t t = v/a = vf-vi / a t = (85 -25) / .7 = (60 mi/hr / .7 m/s^2) (1609 m/mi / 3600s/h) = 38.3 seconds 2. h1 = height above 29.5 m h2 = 29.5 htotal = h1 + h2 t2 = 1.05 s g = 9.8 v0 = 0 for free fall First: find out velocity at top of 29.5 m h2 = v2t2 + 1/2g(t2)^2 29.5 = v2(1.05) + 1/2(9.8)(1.05)^2 v = 22.95 m/s^2 Find h1 (height above 40 m that the object started to free fall v2^2 - v0^2 = 2gh 22.95^2 - 0^2 = 2(9.8)(h1) H1 = 26.87 m Total height: 29.5 + 26.87 = 56.4 m
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