Let’s solve each part step by step.
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1. Define Mass:
Mass is how much “stuff” (matter) is in an object. It doesn’t change no matter where you are — on Earth, on the Moon, or in space. We measure mass in kilograms (kg).
Example: A bag of sugar has a mass of 1 kg whether it’s on your kitchen table or on the Moon.
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2. Define Weight:
Weight is the force of gravity pulling on an object’s mass. It can change depending on where you are because gravity is different in different places. We measure weight in newtons (N).
Formula:
Weight = Mass × Gravity
or
W = m × g
On Earth, gravity (g) is about
9.8 N/kg.
Example: If your mass is 50 kg, your weight on Earth is:
50 kg × 9.8 N/kg = 490 N
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3. Describe what will happen if anything in mass and weights when you go to the moon.
- Your
mass stays the same. You’re still made of the same amount of stuff.
- Your
weight changes because the Moon’s gravity is weaker than Earth’s.
- The Moon’s gravity is about
1/6th of Earth’s gravity.
So if you weigh 600 N on Earth, you’d weigh only about 100 N on the Moon.
But your mass? Still the same!
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4. Why would this happen?
Because weight depends on gravity, and the Moon has less mass than Earth, so its gravitational pull is weaker. Since weight = mass × gravity, if gravity goes down, weight goes down — even though mass doesn’t change.
Think of it like this: On Earth, gravity pulls you down hard. On the Moon, it pulls you down gently — so you feel lighter, but you’re not actually losing any “stuff.”
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5. Find the weight of a 50 kg astronaut on earth.
Use the formula:
Weight = Mass × Gravity
Mass = 50 kg
Gravity on Earth = 9.8 N/kg
Weight = 50 × 9.8 =
490 N
✔ Check: 50 × 10 = 500, so 50 × 9.8 should be a bit less → 490 makes sense.
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6. Find the weight of the same object on a planet where the gravitational attraction has been reduced to 1/10 of the earth’s value. Show all work.
First, find the new gravity:
Earth’s gravity = 9.8 N/kg
New gravity = 1/10 × 9.8 =
0.98 N/kg
Now use the formula again:
Weight = Mass × New Gravity
Weight = 50 kg × 0.98 N/kg =
49 N
✔ Check: 50 × 1 = 50, so 50 × 0.98 should be just under 50 → 49 is correct.
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Final Answer:
1. Mass is the amount of matter in an object, measured in kg. It does not change with location.
2. Weight is the force of gravity on an object, measured in N. It changes with gravity. Formula: W = m × g.
3. On the Moon, mass stays the same, but weight becomes about 1/6 of Earth’s weight.
4. This happens because the Moon’s gravity is weaker than Earth’s.
5. Weight of 50 kg astronaut on Earth:
490 N
6. Weight on planet with 1/10 Earth’s gravity:
49 N
Parent Tip: Review the logic above to help your child master the concept of physical science mass and weight worksheet answer key.
