A body of mass 40 kg stands on a weighing machine in an accerated lift. The reading on the scale of the weighing machine is 300 N. Find tge magnitude and direction of accekeration
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m=40kg
F=300N
suppose that g=9.8m/s²
Now, when the lift goes down, 2 types of accelerations are applied,
1. gravitational acceleration
2.acceleration of life
By thinking about the FBD of the lift,
if the lift moves down, the sum of acceleration = g-a
and if it moves up, it is g+a
[why? Becuase when the life moves, an illusory acceleration is applied on it, which is 'a' here]
That means,
1. if the lift is moving upwards,
F=m(g+a)
300=40(10+a)
a= -2/5 m/s²
2. if lift is going down,
F=m(g-a)
300=40(10-a)
a= +2/5 m/s²
Now the directions:
1.if the lift moves downwards, the magnitude of acceleration is +2/5 m/s²
2.if the lift moves downwards, the magnitude of acceleration is -2/5 m/s²
Hope it helped.
F=300N
suppose that g=9.8m/s²
Now, when the lift goes down, 2 types of accelerations are applied,
1. gravitational acceleration
2.acceleration of life
By thinking about the FBD of the lift,
if the lift moves down, the sum of acceleration = g-a
and if it moves up, it is g+a
[why? Becuase when the life moves, an illusory acceleration is applied on it, which is 'a' here]
That means,
1. if the lift is moving upwards,
F=m(g+a)
300=40(10+a)
a= -2/5 m/s²
2. if lift is going down,
F=m(g-a)
300=40(10-a)
a= +2/5 m/s²
Now the directions:
1.if the lift moves downwards, the magnitude of acceleration is +2/5 m/s²
2.if the lift moves downwards, the magnitude of acceleration is -2/5 m/s²
Hope it helped.
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