Force Problem all my answers don't work

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liamtcarroll
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Assume you are on a planet similar to Earth
where the acceleration of gravity is approximately 10 m/s
and the positive directions for
displacement, velocity, and acceleration are
upward.
At time t = 0 s, an elevator is at a displacement of x = 0 m with a velocity of v = 0 m/s.
A student whose normal weight is 400 N
stands on a scale in an elevator and records
the scale reading as a function of time.

0-5sec------400
5-10sec-----700
10-15sec----0
15-20sec----200what is the velocity of the elevator at the end of 20 sec
 
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What does the scale measure?

Maybe a hint: if the elevator and person are not moving, the force the scale applies to the person standing on it must equal what?
 
You need to determine the acceleration of the student during each period. Then draw a acceleration vs time graph and integrate it up to 20 s.
 
liamtcarroll said:
Assume you are on a planet similar to Earth
where the acceleration of gravity is approximately 10 m/s
and the positive directions for
displacement, velocity, and acceleration are
upward.
At time t = 0 s, an elevator is at a displacement of x = 0 m with a velocity of v = 0 m/s.
A student whose normal weight is 400 N
stands on a scale in an elevator and records
the scale reading as a function of time.

0-5sec------400
5-10sec-----700
10-15sec----0
15-20sec----200


what is the velocity of the elevator at the end of 20 sec

Stop posting questions showing zero effort. You *must* show your attempt at a solution in your schoolwork posts. Check your PMs.