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## Homework Statement

During a certain time interval, the angular position of a swinging door is described by θ = 4.92 + 10.7

*t*+ 2.07

*t*2, where θ is in radians and

*t*is in seconds. Determine the angular position, angular speed, and angular acceleration of the door at the following times.

first at t=0s

then at t=3.10s

finding for each time interval [/B]

θ=

ω=

α=

## Homework Equations

dθ/dt

dω/dt [/B]

## The Attempt at a Solution

so finding the angular position for t=0 i just took the 4.92 because both other parts are multiplied by time which here was 0 hence 4.92+0+0 and for t=3.10 just entered that time into that equation for θ and got 57.98 which was correct. When i tried to find ω at t=0 because ω=Δθ/Δt and you cant have denominator as 0 i thought they were trying to say that it had no angular speed at t=o which seems to make sense, but the answer wasnt 0 and same thing for angular acceleration.

then for t=3.10

ω=Δθ/Δt and got 4.56 rad/s which was also wrong and so was the angular acceleration.

am i meant to be using instantaneous angular speed and acceleration? if so how do i do that?[/B]