Chapter 5: Exercises with Solutions

Chapter 5Quadratic Functions29. We’re given v 0 = 30 m/s, a = 2.5 m/s 2 , and t = 10 s, and asked to find v and x.We will thus need to use both formulas. For the velocity,v = v 0 + at= 30 m (s + 2.5 m/s )× 10 ss= 30 m s + 25m s= 55 m/sFor the distance traveled, x 0 = 0 m since the rocket hasn’t traveled any distance attime t = 0 s.x = x 0 + v 0 t + 1 2 at2= 0 m + (30 m s × 10 s) + (1 2 × 2.5m s 2 × (10 s)2 )= 0 m + (30 m s × 10 s) + (1 2 × 2.5m s 2 × 100 s2 )= 0 m + (30 m s × 10 s) + (1 2 × 2.5m s 2 × 100 s2 )= 0 m + 300 m + 125 m= 425 m31. We’re given v 0 = 88 ft/s, v = 58 ft/s, and t = 10 s, and asked to find a and x.We will thus need to use both formulas. First, since we know v, v 0 , and t, compute a.Solve the velocity formula for a:v = v 0 + atv − v 0 = atAnd plug in the known values:at = v − v 0a = v − v 0ta = v − v 0t58 ft/s − 88 ft/s=10 s−30 ft/s=10 s= −30 ft s × 110 s= −3 ft/s 2Version: Fall 2007