Which planet would a spaceship need the largest force to take off?

Weight = mass * gravitational field strength

W = mg

The force to lift off is the force to overcome the force of weight.

As the mass doesn't change, the only variable affecting W is g, the gravitational field strength.

Which planet has the highest gravitational field strength, and that is your answer. (you probably have this in a data book or something, for reference, earth's gravitational field strength is 9.81 ms^-2 , sometimes simplified to 9.8 or 10)

Once you have worked out your answer, you should have got the planet: Jupiter.

I hope this helped,

Ibraheem.U