A body weighs 700 gram-weight on the surface of the Earth. What will it weigh on the surface of a planet whose mass is 1/7 of Earth's mass and whose radius is half of Earth's radius?
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A body weighs 700 gram-weight on the surface of the Earth. What will it weigh on the surface of a planet whose mass is 1/7 of Earth's mass and whose radius is half of Earth's radius?

G1 Physics · Accepted Answer

Step 1: Surface gravity scales as g∝M/R². For the planet, M′=M/7 and R′=R/2. Step 2: g′/g=(1/7)/(1/2)²=(1/7)/(1/4)=4/7. Step 3: Weight'=700×4/7=400 gram-weight. Final: B.