word problem

Question

Don is a lineman for a utility company and is working on a telephone pole 45 feet above the ground, replacing a transformer that was damaged during a lightning storm. Don's cable cutters fall out of his tool belt and onto the ground. The height, h (in feet), of his cable cutters after t seconds is modeled by the equation
h = −16t^2 + 45,where t ≥ 0.

(a) Find the height of Don's cable cutters after 0.5 seconds.

(b) When will his cable cutters be 10 feet above the ground? Round your answer to 3 decimal places

 

 

(c) When do the cable cutters reach ground level? Round answer to the nearest hundredth of a second.

Answer 1

h = −16t² + 45,   where t ≥ 0

 

  (a) When t=0.5,

         h = -16(0.5)² + 45

         h = 31 feet

 

  (b) What is t when h=10 feet?

         10 = -16t² + 45

         16t² = 35

           t² = 35/16

           t =  1.479 seconds

 

  (c) What is t when h=0 (the ground)?

          0 = -16t² + 45

          16t² = 45

           t² = 45/16

           t = 1.68 seconds