Lbs

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Common misperception. Pound is a unit of force. That's why in those ubiquitous truck ads they glorify their engines generating 230891262211 ft-lbs of torque.
 
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i believe weight takes force due to gravity (g) into account whereas force can be applied in the absence of gravity. not entirely sure though
 
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Weight is force with acceleration fixed to Earth's gravity. If you went to Venus, weight means nothing.
 
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Of course, it is a matter of definition. If I remember correctly then weight is defined(in a strict sense) as a force which is opposite to the normal force of the support (N). So if elevator is falling down with acceleration "a", weight will be defined as m(g-a)... That gives us, If a=g, then weight=0(weightless)
Being a force, weight can be measured in different units, for SI it is kg*m/sec^2 or newtons. However, there is a very old unit called kilogram-force, which is for most applications equal to mass.It was defined as a force that need to be applied to the mass to achieve acceleration equal 9.81... I doubt that MCAT can use this kilogram-force due to ambiguity and archaic.

Sometimes a saw problems that even do not differentiate between weight and mass due to the nature of the question. You may complain that they are not correct, but that will not help 🙂. So I use the context of the problem in order to figure out if the author of the problem is tricky enough to distinguish between weight and mass.
 
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lb is the english units for weight. the mass unit in the english system is a slug i believe.

if you took a 100lb object to the moon, you know it would be less lbs, so you know it can't be mass, which wouldn't change.
 
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