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A lift of mass 1000 kg is moving up with a speed of 6 m/s. In order to stop it brakes...

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lovekblue | Student, Grade 11 | Salutatorian

Posted February 12, 2012 at 9:07 AM via web

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A lift of mass 1000 kg is moving up with a speed of 6 m/s. In order to stop it brakes are applied. If the downward acceleration generated is 2 m/s^2, find

(a)    The time in which the lift stops.

(b)   The distance it covers before coming to a halt.

(c)    The tension in to cable supporting lift during the acceleration.

 

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted February 12, 2012 at 11:36 AM (Answer #1)

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A lift of mass 1000 kg is moving up with a speed of 6 m/s. In order to stop it brakes are applied. Due to this there is a downward acceleration generated of 2 m/s^2.

Taking the downwards direction as positive, initially the lift moves at -6 m/s. The acceleration is 2 m/s^2. If the time it comes to a halt in is t seconds. 0 = -6 +2*t

=> t = 3 s

If the distance covered by the lift before it comes to a halt is s:

-(-6)^2 = 2*2*s

=> s = 36/4 = 9 m

The tension in the cable supporting the lift is the force pulling the lift downwards. This is equal to F = m*a = 2*1000 = 2000 N.

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