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UAM Formulae. Example questions. Free fall q 1. A chemistry text book is thrown downwards at 13.00 m/s from the top of a 25.00 m high building. What is the final velocity when it just hits the ground? How long will it take to reach the ground? How far did it fall in the 1 st second?.
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UAM Formulae Example questions
Free fall q 1 • A chemistry text book is thrown downwards at 13.00 m/s from the top of a 25.00 m high building. • What is the final velocity when it just hits the ground? • How long will it take to reach the ground? • How far did it fall in the 1st second?
Free fall q 1 a) Choose the appropriate formula; as we do not have time, use: vf2 = vi2 + 2aΔd = (-13.00 m/s)2 + 2(-9.81 m/s2)(-25.00 m) vf = - 25.7 m/s or 25.7 m/s [down]
Free fall q 1 b) How long means find Δt: Δt = (vf – vi)/a = [-25.7 m/s – (-13.00 m/s)]/(-9.81 m/s2) = 1.29 s
Free fall q 1 c) The 1st second is from t = 0 s to t = 1 s. (The 3rd second would be between 2s and 3s). We need to find the distance travelled for 0s and 1 s and subtract.
Free fall q 1 Δdo at t = 0 is 0m Δd1 at t = 1 s is found using the Big 4: Δd1 = viΔt + ½aΔt2 = (-13.00 m.s)(1s) + ½(-9.81 m/s2)(1s)2 = -17.9 m Therefore Δd = -17.9 m – 0 = -17.9 m The text fell -17.9 m in the 1st second.
Free fall q 2 • A biologist is projected vertically upwards, by large springs, from the ground at 12.0 m/s. • When does the biologist reach maximum height? • What is the velocity of the biologist just at it reaches the ground? • How long is the biologist in the air? • What is the maximum height? • What is the acceleration at the maximum height?
Text questions - kinematics • pg 41 Q# 1 – 5, 7, 9 – 14, 16, 17 • MISQ # 1 – 9 • pg43 # 1 – 5, 7 – 13, 15, 17 – 35, 38, 39 – 51, 53, 55 – 59, 62, 64, 65, 68, 71, 78, 79