Question

I need help with number 23!! Please

Answer 1

Ah hah !  There's an easy way and a hard way to do this one.
If it's OK with you, I'm gonna do it the easy way, and not even
talk about the hard way !

First, let's look at a few things in this question.

-- "gravitational force between a planet and a mass"
    This is just a complicated way to say "How much does the mass weigh ?"
    That's what we have to find.

-- If we know the mass, how do we find the weight ?
   Multiply the mass by the acceleration of gravity there.
   Weight = (mass) x (gravity) .

-- Do we know the acceleration of gravity on this dark mysterious planet ?
    We do if we read the second line of the question !  
    It's right there ... 8.8 m/s² .

-- We know the mass.  We know gravity.  And we know that
    if you multiply them, you get the weight (forced of gravity).

I'm pretty sure that you can do the rest of the solution now.

weight = (mass) x (gravity)

Weight = (17 kg) x (8.8 m/s²)

Multiply them:

Weight = 149.6  kg-m/s²

That complicated-looking unit is the definition of a Newton !

So the weight is  149.6 Newtons.  That's the answer.  It's choice-A.
It's about 33.6 pounds.

When this mass is on the Earth, it weighs about 37.5 pounds.
But when it's on this planet, it only weighs about 33.6 pounds.
That's because gravity is less on this planet. (8.8 there, 9.8 on Earth)