Question

1a )A man with a parcel stands in a lift. If none are moving, the weights are 29.4N, 539N, and 19600N respectively. Find the magnitude of the tension in the parcel string, the force exerted by the man on the floor of the lift, and the tension in the lift cable.

b) The same lift now starts to move due to an increase in the lift cable's tension to 22226.4N, causing a resultant force of 2000N on the lift and a resultant of 55N on the man. Find the new tension in the parcel's string.

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Answer 1

(a) initialy as the lift is not moving the tension in the parcel string will be equals to the weight of the parcel which is 539N

the force exerted by man on the floor will be equals to the sum of the weight of the parcel and weight of the man which is 29.4+539=568.4N

the  tension in the lift cable should be equals too the sum of weight of lift,parcel,man = 29.4+539+19600=20168.4

(b)as now lift is moving ans cause a net force on the man 55N. which means motion of lift apply an extra force of 55-29.4=25.6N on the man

so man got an accelaration of 25.6*10/29.4=8.7 ms2

and no same accelartion is applied on the parcel also cause its net accelartion =10+8.7=18.7 ms2

and now its weight wiil be = 539*18.7/10= 1007.9 N

and the tension in the parcel string will be equals to the weight of the parcel = 1007.9N