Question

When you lift one foot up so that you are standing on one foot, does the reading change? Does a scale read force or pressure?

Answer 1

Hint:The scale gives the reading of how much a body weighs and the weight of a body is the force with which the earth attracts it. The force on a body due to earth’s attraction is called the force of gravity and it does not depend on the area.

Complete step by step answer:
When you lift your one foot up so that now you are standing on one foot, the reading of the scale does not change because the weighing scale measures the weight of the body. In other words, it determines the force exerted by the body on the scale. Force is defined as the physical cause which either changes the shape or size or state of rest or motion. The force exerted by a body depends on the mass of the body and acceleration (in this case, it is the acceleration due to gravity). As both mass and acceleration remain the same, therefore the force (weight) is also constant and hence the scale gives the same reading in both the cases. A scale reads force and the value given by it is actually the normal force exerted back by the scale on the body to support the weight of the body by balancing with it.
Pressure is defined as the force per unit area. So, if the scale would have measure pressure then the reading would have changed as the area changes because the foot is being lifted up. Pressure is measured by barometer, manometer etc.

Note:Scale measures how much an object weighs i.e. force which means the force acting between the object that you are weighing and the gravitational force of the earth. The value of acceleration due to gravity remains the same even when you lift your one foot up and so the reading also remains the same.