. An elevator cab that weighs 27.8 kN moves upward. What is the tension in the cable if the cab’s speed is (a) increasing at a rate of 1.22 m/s2 and (b) decreasing at a rete of 1.22 m/s2?

Explanation:

It is given that, = 27.8 kN =

Now, formula for the mass of elevator is as follows.

                m =

                    =

                    = kg

(a)   When acceleration is increasing at a rate of 1.22 . Force according to the Newton's second law of motion is as follows.

               F = T - mg = ma

            T =

Hence, tension in the cable if the cab’s speed is increasing at a rate of 1.22 is .

(b)   When acceleration is decreasing at a rate of 1.22 . Force according to the Newton's second law of motion is as follows.

                      F = T - mg = ma

            T =

Hence, tension in the cable if the cab’s speed is decreasing at a rate of 1.22 is .

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the part of the wave he is travelling on is the crest