Barron's 2nd Edition DT Q26

Barron's Book

26) We are given a situation where a 50 kg person is standing on a scale in an elevator accelerating at 1 meter per second squared. Now we need to find the weight of the person measured from a scale.

Many people get this type of problem wrong because they fail to recognize that a scale measures the normal force, not the weight. Let’s draw a diagram to help us visualize what is happening in this situation.

Where N is normal force, W is weight, m is mass and a is acceleration

Next, we should sum the forces and substitute our known values to solve for the normal force.

Where F is net force, N is normal force, W is weight, m is mass, a is acceleration, and g is acceleration due to gravity

Answer: E