3A5 Weight, Mass, and Density Flashcards
Explore the relationship between weight, density, and mass. (56 cards)
Define:
Mass
The amount of matter in an object.
Mass is constant regardless of location.
What are the common units of mass?
Some common units used are:
- Grams (g)
- Kilograms (kg)
- Pounds (lbs)
Mass can be measured in various units depending on the system used.
Define:
Weight
The downward force acting upon an object due to gravity.
Weight varies based on the strength of gravity at different locations. The equation is represented by W=mg, where m is equal to mass and g is equal to the force of gravity.
What is the difference between mass and weight?
- Mass is the amount of matter in an object.
- Weight is the gravitational force acting on that mass.
Mass is measured in kilograms (kg) and weight in newtons (N).
What misconception do people often have about weight and mass?
People often use “weight” and “mass” interchangeably, though they are distinct concepts.
Weight depends on gravity, while mass is intrinsic to the object.
True or false:
Mass remains constant, but weight changes depending on gravity.
True
Weight depends on the local gravitational acceleration (e.g., it’s lower on the Moon).
Fill in the blank:
Weight is a _____ quantity, while mass is a scalar quantity.
vector
Weight has both magnitude and direction, but mass only has magnitude.
Why is weight considered a force?
Because it is the result of gravitational acceleration acting on mass.
Weight follows F=mg,
where “F” is force (i.e., weight), “m” is mass and “g” is gravitational acceleration.
What is the SI unit of weight?
Newton (N)
Weight is a force.
Calculate the weight of a 10 kg object on Earth.
Weight = 10kg × 9.8m/s² = 98N
For this equation, use g = 9.8 m/s² to represent the acceleration due to gravity.
True or false:
An object’s mass changes if it’s taken to the Moon.
False
Mass remains constant regardless of location; only weight changes.
How can weight vary even if mass remains constant?
Weight changes due to variations in gravitational acceleration, such as on different planets.
g depends on the mass and radius of the celestial body.
How does weight vary on the Moon compared to Earth?
Weight on the Moon is approximately 1/6 of the weight on Earth due to weaker gravity.
The Moon’s gravitational acceleration is about 1.63m/s²
What happens to a person’s weight in outer space?
It becomes negligible because they are in free fall, experiencing microgravity, even though their mass remains unchanged.
Weight depends on gravitational force, which is much weaker in outer space.
True or false:
Weightlessness means the absence of mass.
False
Weightlessness occurs when there is no force supporting the object, but mass remains constant.
Why do astronauts experience weightlessness in space?
Because they are in free-fall along with their spacecraft, constantly falling towards Earth but never hitting it.
Weightlessness occurs when no normal force counters gravity, as in orbiting spacecraft.
Does weightlessness mean zero gravity?
No - gravity still acts, but there’s no support force to resist it.
Gravity is still acting on the object, but its effects are not felt due to free-fall conditions.
How does the weight of an object vary at the poles and the equator?
Weight is slightly higher at the poles due to stronger gravitational acceleration.
Earth’s shape causes gravity to be weaker at the equator.
Why do objects weigh less at higher altitudes?
Gravitational acceleration decreases as the distance from Earth’s center increases.
The effect is negligible for most everyday altitudes but noticeable on mountains.
Fill in the blank:
On Jupiter, a person’s weight would ______ compared to Earth
increase
Jupiter’s stronger gravity increases the weight of the same mass.
Give an example of how weight is used in designing safety equipment.
Parachutes are designed to counteract weight with air resistance for safe descent.
Understanding weight helps optimize safety designs and material strength. Weight affects helmets, airbags, and parachutes to reduce impact forces.
What happens to an object’s weight when submerged in water?
The apparent weight decreases due to the buoyant force of the displaced water.
Weight measured underwater is less than actual weight in air.
What device is used to measure mass rather than weight?
A balance or beam scale.
Balances compare masses directly, independent of gravitational variations.
How does a scale measure weight?
A scale measures the gravitational force acting on an object and converts it into a weight reading.
Digital and mechanical scales use different mechanisms but rely on W=mg.