D. DCne e total displacement of the bus.(ans: 47 x10 m) 4. In a 100.0 m sprint,
ID: 1884609 • Letter: D
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D. DCne e total displacement of the bus.(ans: 47 x10 m) 4. In a 100.0 m sprint, a runner starts from rest and accelerates to 9.6 m/s (W in 4.2 s. (a) Calculate the acceleration of the runner, (ans: 2.3 m/s' (WI (b) Calculate the displacement of the runner. [ans: 2.0 x 10' m (W (c) The runner runs at a constant velocity for the rest of the race. What is the total time? (ans: 13 5. Two football players separated by 42 m run directly toward each other. Football player 1 starts from rest and accelerates at 2.4 m/s2 [right), and football player 2 moves uniformly at 5.4 m/s [left] aA (a) How long does it take for the players to collide? (ans: 4.1 (b) How far does each player move? (ans: player 1: 20 m; player 2: 22 m) (c) How fast is football player 1 moving when the players collide? (ans: 9.8m/s] 6. A jet lands on a runway at 110 m/s [forward]. When stopping, the jet can accelerate at 6.2 m/s2 (backward]. (a) Calculate the minimum time for the jet to stop. (ans: 18 s (b) What is the minimum safe length for this runway? (ans: 9.8 x 10° m) (C) Explain why the runway should be much longer than the minimum safe length.Explanation / Answer
here,
4)
final speed , v = 9.6 m/s
time taken , t = 4.2 s
a)
let the accelration be a
v = u + a * t
9.6 = 0 + 4.2 * a
a = 2.3 m/s^2
b)
the displacement of the runner , s1 = 0 + 0.5 * a * t^2
s1 = 0 + 0.5 * 2.3 * 4.2^2 m
s1 = 20 m = 2 * 10^1 m
c)
the total time taken , t2 = t + (s - s1)/v
t2 = 4.2 + ( 100 - 20)/9.6 s
t2 = 13 s
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