how does mass differ from weight

Answer 1

Mass and weight are related but distinct concepts in physics.

1. Mass:

   • Definition: Mass is a measure of the amount of matter in an object. It is a scalar quantity, meaning it has only magnitude and no direction.
   • Units: Mass is typically measured in kilograms (kg), grams (g), or other units in the metric system.
   • Independence: Mass remains constant regardless of the object's location. Whether an object is on Earth, the Moon, or in space, its mass does not change.

2. Weight:

   • Definition: Weight is the force exerted on an object due to gravity. It depends on both the mass of the object and the gravitational acceleration acting on it.
   • Formula: Weight can be calculated using the formula \( W = m \times g \), where \( W \) is weight, \( m \) is mass, and \( g \) is the acceleration due to gravity (approximately \( 9.81 , \text{m/s}^2 \) on Earth).
   • Units: Weight is measured in newtons (N) in the metric system, as it is a force.
   • Variability: Weight can change depending on the gravitational field strength. For example, an object would weigh less on the Moon than on Earth because the Moon's gravitational acceleration is weaker.

In summary, mass is a measure of how much matter is in an object, while weight is the force that results from the gravitational pull on that mass.

Answer 2

a block of wood floats on water. why is this

Answer 3

A block of wood floats on water due to the principle of buoyancy, which is described by Archimedes' principle. Here's how it works:

1. Density: For an object to float, its density must be less than the density of the fluid it is in. Wood typically has a density lower than that of water, which is why it floats. The density of water is about \(1 , \text{g/cm}^3\) (or \(1000 , \text{kg/m}^3\)), while most types of wood have a density less than this.

2. Buoyancy: When the wooden block is placed in water, it displaces a volume of water equal to the submerged part of the block. According to Archimedes' principle, the buoyant force acting on the block is equal to the weight of the water displaced by the submerged part of the block.

3. Equilibrium: The block will float as long as the buoyant force is equal to or greater than its weight. As long as the weight of the block is less than the weight of the water displaced, it will float. If the weight of the block is greater than the buoyant force, it will sink.

In summary, a block of wood floats on water because its density is lower than that of water, and it experiences a buoyant force that supports its weight, allowing it to stay afloat.