A boy in a hot air balloon drops his cellular phone when the balloon is 150 ft above the ground and rising at the rate of 10 ft/s.
a.How long will it take the cellular phone to reach the ground?
b. With what speed will it strike the ground?
a. "h(t)=150+10t-16t^2."
"h(t)=0 \\to 150+10t-16t^2=0 \\to t=\\frac{5+\\sqrt{25+9600}}{32}=3.39 s."
The cellular reaches the ground in 3.39 seconds.
b. "v(t)=10-32t."
"v(3.39)=10-32*3.39=-98.48ft\/s."
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