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# A lift is accelerated upward. Will the apparent weight of a person inside the lift increase, decrease or remain the same relative to its real weight? If the lift is going with uniform speed, then?

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Thd apparent weight of the person will increase. When in uniform speed then acceleration is zero, so no change in weight.

Physics - The Science Cube

Put yourself on a weighing scales inside a stationery elevator. So your velocity here is zero meters per second. Let us examine what are the forces acting on your body. We know one of the force is “mg” which acts in the downward direction.The weighing scale will push you up with a certain...

Put yourself on a weighing scales inside a stationery elevator. So your velocity here is zero meters per second. Let us examine what are the forces acting on your body. We know one of the force is “mg” which acts in the downward direction.The weighing scale will push you up with a certain force which is nothing but the Normal reaction and shows up as weight “W” on the weighing scale (We will take any vector pointing in the upward direction as positive and any vector acting in the downward direction as negative).

We write the forces acting on your body in accordance with Newton's second law of motion which says that the net force acting on you or on a body is equal to its mass into the acceleration induced or

F net = m X a

There are 2 forces acting on the body  (1) mg acting in downward direction and we take it as a negative vector and (2) The normal reaction from the floor lift that is the weight or W (we take it as a positive vector since it points upwards)

So the net force is = W – mg and this should equal the product of resultant acceleration with mass. So the equation that will form is

F net = W - mg = ma

Or                  W = mg + ma

So if the lift is stationery, a = 0 and W = mg the way it should be. You simply see your weight in the scale

But if the lift starts accelerating up so that velocity increases resulting in positive acceleration “a”. We see that the entity “ma” in above equation adds to mg and therefore the weight W increase.

But if the lift is moving up with a uniform velocity, acceleration “a” will become zero (since acceleration happens only when velocity changes). In such a case again, W = mg or no change

Now imagine that you are reaching the top floor. The lift will start slowing down and this can happen only if a force acts on the lift in the opposite direction. Hence the acceleration “a” now is in downward direction hence negative. So the above equation will now become

W = mg + m X (-a) or

W = mg – ma

So you see when the lift is slowing down at the top, your weight will now reduce by “ma”.

Physicist

if the lift accelerated in upward direction then the apparent weight of the person increase and when lift going with uniform speed then the apparent weight is equal to actual weight of the person.

When lift accelerates upward, then normal rx,N = mg+ma Where mg= actual weight and a= acceleration Therefore normal reaction which is apparent weight increases.. But if lift moves with Uniform speed then acceleration=0 Therefore apparent weight=ma I.e no change in weight

When lift accelerates upward, then normal rx,N = mg+ma

Where mg= actual weight and a= acceleration

Therefore normal reaction which is apparent weight increases.. But if lift moves with Uniform speed then acceleration=0

Therefore apparent weight=ma

I.e no change in weight

Physics Lecturer

When lift is going upward with acceleration than the apparent weight will decrease because the motion is in the opposite direction of Mg or real weight. When lift is going upward with uniform speed than the weight will be -ve of the real weight

N-m.g =m.a N=m.g+m.a which is apparent weight. Hence increase in first case. In second case a=0 so same.

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When the lift accelerates upward, a pseudo force will act on the body in the downward direction in addition to the weight. So the apparent weight will increase. If lift is going with uniform speed, the force acting on the body will be weight of the person. So the apparent weight will be same as the...
When the lift accelerates upward, a pseudo force will act on the body in the downward direction in addition to the weight. So the apparent weight will increase. If lift is going with uniform speed, the force acting on the body will be weight of the person. So the apparent weight will be same as the real weight. read less

Tutor

When the lift accelerates upward, a pseudo force will act on the body in the downward direction in addition to the weight. So the apparent weight will increase. If lift is going with uniform speed, the force acting on the body will be weight of the person. So the apparent weight will be same as the...
When the lift accelerates upward, a pseudo force will act on the body in the downward direction in addition to the weight. So the apparent weight will increase. If lift is going with uniform speed, the force acting on the body will be weight of the person. So the apparent weight will be same as the real weight. read less

Computer Wizard

increase

Mentor/ Tutor

1) Increase 2) remain same

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