Physics: Weight Calculation and Mass Units

Weight Calculation

• Weight (w) is the force exerted on an object by gravity
• Weight is calculated using the formula: w = mg
• m is the mass of the object
• g is the acceleration due to gravity (approximately 9.8 m/s² on Earth)

Mass Units

• Mass is a measure of the amount of matter in an object
• Common units of mass include:
  • Grams (g)
  • Kilograms (kg)
  • Milligrams (mg)
  • Tonnes (t)

Applications in Physics

• The formula w = mg is used to calculate the weight of objects in various situations, such as:
  • Objects on or near the surface of the Earth
  • Objects in free fall
  • Objects on inclined planes
  • Objects in motion under the influence of gravity

Force of Gravity

• The force of gravity is a universal force that attracts two objects with mass towards each other
• The force of gravity is responsible for keeping objects on the surface of the Earth
• The strength of the force of gravity depends on the mass of the objects and the distance between them

Gravity on Different Planets

• The acceleration due to gravity (g) varies on different planets and celestial bodies
• For example:
  • On the Moon, g ≈ 1.62 m/s²
  • On Mars, g ≈ 3.71 m/s²
  • On Jupiter, g ≈ 24.79 m/s²
• This affects the weight of objects on different planets, even if their mass remains the same

Weight Calculation

• Weight is the force exerted on an object by gravity, calculated using the formula: w = mg.
• The mass of the object (m) and the acceleration due to gravity (g) are the key factors in weight calculation.

Mass and Its Units

• Mass is a measure of the amount of matter in an object, with common units including:
  • Grams (g)
  • Kilograms (kg)
  • Milligrams (mg)
  • Tonnes (t)

Applications of Weight Formula

• The formula w = mg is used to calculate the weight of objects in various situations, including:
  • Objects on or near the surface of the Earth
  • Objects in free fall
  • Objects on inclined planes
  • Objects in motion under the influence of gravity

Force of Gravity

• Gravity is a universal force that attracts two objects with mass towards each other, responsible for keeping objects on the surface of the Earth.
• The strength of the force of gravity depends on the mass of the objects and the distance between them.

Gravity on Different Planets

• The acceleration due to gravity (g) varies on different planets and celestial bodies, affecting the weight of objects:
  • On the Moon, g ≈ 1.62 m/s²
  • On Mars, g ≈ 3.71 m/s²
  • On Jupiter, g ≈ 24.79 m/s²
• This means that an object's weight changes on different planets, even if its mass remains the same.

Here's a quiz based on the study notes:

• Quiz: Weight Calculation using w = mg*
• Section 1: Multiple Choice*
• What is the force exerted on an object by gravity called?
  • Mass
  • Weight
  • Gravity
  • Acceleration
• What is the unit of acceleration due to gravity on Earth?
  • m/s
  • m/s²
  • km/s
  • g/s
• What is the mass unit that is equal to 1000 grams?
  • Tonnes
  • Kilograms
  • Grams
  • Milligrams
• Section 2: Short Answer*
• Calculate the weight of an object with a mass of 20 kg on Earth. (Answer: w = 20 kg × 9.8 m/s² = 196 N)
• What is the mass of an object that weighs 50 N on the Moon, given g = 1.62 m/s²? (Answer: m = 50 N / 1.62 m/s² = 30.86 kg)
• What is the acceleration due to gravity on Jupiter, given that an object weighs 240 N on Jupiter and 30 N on Earth? (Answer: g = 240 N / 30 N × 9.8 m/s² = 24.79 m/s²)
• Section 3: Essay Question*
• Describe the difference between mass and weight, and explain how the formula w = mg is used to calculate the weight of an object on different planets.