Gravitational field intensity (help)

[waxer1987]

I have this assignment in physics class and I'm stuck on this 1 question.

What we were doing: We were hanging 0.10kg, 0.20kg weights etc.. on a Newton scale and we were recording the force of gravity. For 0.10kg I recorded 1 N, 0.20kg was 2 N, and so on until 1kg was 10 N.

So the question is: Write and equation relating force of gravity, mass, and the numerical value of the gravitational field intensity of Earth from this activity.

I was thinking Fnet = ma, so 1 N = 0.10kg a. Probably way off.

Any help would be greatly appreciated. Thank you.

 

[fleem]

Hints:

Can you think of a simple arithmetic expression that always remains constant for any of the experiments you did? For example, is the product of the mass and the force a constant for all the experiments? Is the ratio of the mass and force always constant? No need to think about the sum or difference--you never add or subtract values of different units! (You don't add apples and seconds!)

Once you've discovered an expression that remains constant for all the experiments, imagine what would happen on a planet that had, say, twice Earth's gravity and how you'd need to change your expression so that it worked on that planet. Then think of how you might add one more variable to the expression, who's value would indicate the gravity of the planet.

 

[nlightner]

Hello! It seems like you are on the right track with your thinking. The equation you are looking for is actually Fg = mg, where Fg is the force of gravity, m is the mass, and g is the gravitational field intensity. In your experiment, you are measuring the force of gravity (Fg) with the Newton scale and the mass (m) of the weights. The numerical value of the gravitational field intensity of Earth (g) is 9.8 N/kg. So, your equation would look like this: Fg = mg = 0.10kg x 9.8 N/kg = 0.98 N. This means that for every 0.10kg weight you add, the force of gravity will increase by 0.98 N. I hope this helps! Good luck with your assignment.