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/sci/ - Science & Math

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4370489 No.4370489 [Reply] [Original]

hey /sci/ I'm having difficulties with my physics homework. care to help me out?

it's due in an hour.

At what height above the earth is the free-fall acceleration 50% of its value at the surface?

What is the speed of a satellite orbiting at that
height?

in return. here's how fireworks work!

>> No.4370540
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4370540

pokescience

>> No.4370571

halp? :(

>> No.4370586

also,
The centers of a 5.0 kg lead ball and a 50 g lead ball are separated by 7.0 cm.

What gravitational force does each exert on the other? (in newtons)
What is the ratio of this gravitational force to the weight of the 50 g ball?

>> No.4370591

F = ma

Fgrav = GMm/r^2

Frad = mv^2/r

>> No.4370593

just look up gravity on wikipedia. sheesh. also remember gravity drops off at an inverse-square relationship.

So if gravity at earth's surface is g when the distance from center of earth = radius of earth,

acceleration = g/2 when r is root 2 * radius of earth. that wasn't so hard was it?

>> No.4370596

also,

describe mathematically the quantum origins of the gravitational force, and prove that a gravitational wave propagates at the speed of light, c.

>> No.4370599

....I still don't understand. I'm a straight retard at formulas.

>> No.4370628
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4370628

Perhaps you should switch to biology since this physics 1 hw is confounding you.

>> No.4370638

I am switching after this semester, I thought I could do it but I suck at life. and if I fail this class I'll be deficient and have to leave my school.

>> No.4370648

First, how do you find the free-fall acceleration of something on the Earth?

>> No.4370656

>>4370599
Force due to gravity = G*(mass of object)*(mass of planet)/(distance from center)^2

Note that the only thing that CAN change is the distance. If you double the distance, then you're dividing by 4, if you trippe the distance you divide by 9. quadruple, divide by 16 and so on.

Work backwards from that, if I want to divide by 2, what multiple of the distance do you have to be at?

>> No.4370658

I sorta understand the equation. like for the second one it's 6.674e-11m^3/kgs^2(5kg)(.05kg)/7^2

i just dunno how to calculate it. I don't know what e is or how to use it.

>> No.4370665

>>4370658
6.674e-11 here means 6.674 * 10^(-11).

>> No.4370685

>>4370656
√2