P(t) models the distance of a swinging pendulum (In CM) from the place it has travelled t seconds after it starts to swing. Here, t is entered in radians. P(t)=−5cos⁡(2πt)+5 What is the first time the pendulum reaches 3.5 CM from the place it was released? Round your final answer to the hundredth of a second. Ok, so I did this to get the solution: 3.5=−5cos⁡(2πt)+5 −1.5=−5cos⁡(2πt) 0.3=cos⁡(2πt) cos−1(0.3)=2πt cos−1(0.3)2π=t The fact is this gives me 11.55 seconds to get to 3.5 CM, which does not sound right. Where did I go wrong and how can I fix it?

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P(t)  models the distance of a swinging pendulum (In CM) from the place it has travelled t seconds after it starts to swing. Here, t is entered in radians.   P(t)=−5cos⁡(2πt)+5   What is the first time the pendulum reaches 3.5 CM from the place it was released?   Round your final answer to the hundredth of a second.    Ok, so I did this to get the solution:    3.5=−5cos⁡(2πt)+5    −1.5=−5cos⁡(2πt)    0.3=cos⁡(2πt)    cos−1(0.3)=2πt    cos−1(0.3)2π=t   The fact is this gives me 11.55 seconds to get to 3.5 CM, which does not sound right. Where did I go wrong and how can I fix it?

Fallbasisz8 · Accepted Answer

Obviously you&#039;re expecting the input to cos in radians because you have 2π  in  cos⁡(2πt). In physics you always use radians.However, you can get it to work in degrees with a slight modification: change 2π to 360. Don&#039;t make it a habit though. Stay away from degrees.

P(t) models the distance of a swinging pendulum (In CM) from the place it has travelled t seconds a

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