SOLUTION: Please help me with my calculus question.It is due tomorrow. A truck travelling along a straight section of highway, on a wet evening, braked suddenly to avoild blinky Bill who ha

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Question 347061: Please help me with my calculus question.It is due tomorrow.
A truck travelling along a straight section of highway, on a wet evening, braked suddenly to avoild blinky Bill who had wandered onto the road off in the distance.The reducing velocity of the truck under braking,v, in metres per second,is modelled by the equation:
v=30e^-t/2 -5
where t is the number of seconds after the brakes were applied.Assume the truck held its line under braking conditions.
1.calculate how long it took the truck to come to a stop. Express your answer as both an exact value and accurate to 2 decimal places.
2. At what time after braking was the truck's velocity 15m/s.Express your answer as both an exact value and accurate to 2 decimal places.
Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
v=30e^-t/2 -5
where t is the number of seconds after the brakes were applied.Assume the truck held its line under braking conditions.
1.calculate how long it took the truck to come to a stop. Express your answer as both an exact value and accurate to 2 decimal places.

-t/2 = ln(1/6)
t = -ln(1/6)/2
t =~ 0.90 seconds
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2. At what time after braking was the truck's velocity 15m/s.Express your answer as both an exact value and accurate to 2 decimal places.

-t/2 = ln(2/3)
t = -ln(2/3)/2
t =~ 0.20 seconds