Explanation:

Weight is the force with which an object is attracted towards the center of the earth due to gravity. It is measured in newtons (N) or in pounds (lb). The correct option is A, which says that weight is measured by a spring balance.

What is a spring balance?

A spring balance is a device that measures weight or force by the extension or compression of a spring. When an object is hung from the spring balance, the spring stretches, and the extension of the spring is proportional to the weight of the object. The spring balance has a calibrated scale that indicates the weight of the object in newtons or pounds.

Why is a spring balance used to measure weight?

A spring balance is used to measure weight because it is simple, accurate, and easy to use. The spring balance is portable and can be carried to different locations, making it useful for measuring weight in the field. Also, the spring balance does not require a level surface to measure weight, unlike a beam balance, which requires a level surface.

Can weight be measured in kg?

Weight is not measured in kg. Kg is a unit of mass, whereas weight is a force. Weight is measured in newtons (N) or pounds (lb). However, the mass of an object can be measured in kg using a balance.

Is weight a scalar or vector quantity?

Weight is a vector quantity because it has both magnitude and direction. The direction of weight is always towards the center of the earth. However, in most cases, weight is treated as a scalar quantity because its direction is always downwards and does not change.