Question

A man weighs 200 pounds on earth. How much would he weigh on a planet four times as massive as the earth with a radius five times as great?

• A. 4000 pounds
• B. 250 pounds
• C. 160 pounds
• D. 10 pounds
• E. 32 pounds

Answer 1

The correct option is E 32 pounds

Here $mg=200$ pounds

We know that earth's surface gravity is $g=\frac{GM}{R^2}$

For the planet, $g^{\prime }=\frac{G\left(4M\right)}{(5R{)}^2}=0.16\frac{GM}{R^2}=0.16g$

The the weight on the planet will be $m{g}^{\prime }=0.16mg=0.16\times 200=32$ pounds