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Answers to Chapter 2 problems

 

 

2.4.1  48 km h−1

2.4.2  v = B + 2Ct; a  =  2C

          At t  = 3  s:   s = 43.9 m; v = 25.3 m s−1; a = 7.6 m s−2.

          At t = 10 s :  s = 407.2 m; v = 78.5 m s−1;  a = 7.6 m s−2

2.4.3  vA – 3Bt2;   a = âˆ’ 6Bt 

          At = 0.5 s: x = 3.75 m; v = 6.5 m s−1 ; a = âˆ’ 6 m s−2.

          At t = 2.0 s : x = 0 m; v = −16 m s-1; a = − 24 m s−2

2.4.4  (a) 0.257 m3 s−1 (b) 0.161 m2 s−1

2.5.1  (a) 85 m (b) − 41 m s−1 (c) 5.2 s

2.5.2   Either strategy, (a) or (b), would work.

2.5.3  (a) The stones do collide (b) 1.89 s (c) 3.29 m (d) First stone is moving downwards, the second stone upwards.

2.5.4  (a) 6.0 s (b)18 m s−1&²Ô²ú²õ±è; (c) 72 m.

2.5.5  (a)128 m (b) 5.1 s (c) 56.5 m s−1

2.5.6  Typical graphical results:

          At t  = 0.5 s: a = − 5.85 m s−2 (compares with − 6 m s-2 from Problem 2.4.3)

          At t = 2.0 s : a = − 23.2 m s−2 (compares with − 24 m s−2 from Problem 2.4.3)

          Change of displacement = − 3.6 m (compares with − 3.75 m from Problem 2.4.3)

 

2.5.7  (a) 2 m s−2 (b) (i) 1 m s−1 (ii) 17 m s−1

 

2.5.8  (a) 28.0 m s−1 upwards (b) 35.7 m s−1 downwards (c) 3.5 m s−1 upwards

2.5.9  v(t) = 60 m s−1 â€“ (9.8 m s−2)t   (a) 60 m s−1  (b) 6.1 s (c) 184 m;  10.0 m s−2

2.5.10  3 m 43.2 s

2.6.1  96.2 m3

2.6.2  (a) maximum at 47.2 m; minimum at −14.4 m (b) minimum at  âˆ’26.8 m s−1 ; no  maximum (tends  to infinity)

2.6.3  p = 10/b + 2b;  8.94 m; l = (a square)

2.7.1  (a) 1.8 rev s−2 = 11.31 rad s−2 (b) 3.33 s (c) 6.67 s (d) 40 rev

2.7.2  (a) −2.3 × 10−9 rad s-2 (b) 2620 yr (c) 0.024 s.

2.7.3  1.525 m;  1.82 m    

2.7.4   âˆ’15.08 rad s−2;  2.5 s

2.7.5   v = 0.3wcoswt;   a = ­− 0.3w2sinwt              0.28 m;  âˆ’ 0.090 m s−1; − 0.171 m s−2.

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