Recent content by mutineer123

1. Why do attractive force have a negative sign? like F= -GMm/r^2

So if there is any difference will the object stay in the orbit or fall down?
2. Why do attractive force have a negative sign? like F= -GMm/r^2

kk got it thanks. Hey can I ask you guys another question? What exactly is the difference between centripetal force and gravitational force?? Are they the same? WHY IS acceleration (of free fall) the (resultant) force of the difference between gravitational and centripetal force??
3. Why do attractive force have a negative sign? like F= -GMm/r^2

Why do attractive force have a negative sign? The book says its because one must be moving toward the other. But how does it make it negative? I dont understand. Can anyone explain the law of gravitation formula?? F= -GMm/r^2
4. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

Yes yes, that substitution escaped me......I did it that way now. But i am not getting the same answer as i did in the mgh way...any suggestions on why?
5. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

I also know mar's gravitational acceleration. But like i said using GMm/r cannot yield anything because like you know, the masses are in ratio. So I dont know the mass! How can I proceed then??
6. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

Are you sure your method will works? u say ΔKE+ΔPE=0 where ΔPE=(GMm/R).(R/R). But you can't use the formula ΔPE=(GMm/R).(R/R) in this way, you don't know the mass of mars!
7. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

How is the final velocity 0? ANd uve written at the beginning "For excape, r=∞', why do we take that assumption?
8. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

I have no idea what you did after your integration. Can u explain?
9. Finding the escape speed in MArs. Problem on advanced gravitational potential energy.

Homework Statement The mean diameters of Mars and Earth are 6.9 10^3 km and 1.3 10^4 km, respectively.? The mass of Mars is 0.11 times Earth's mass. (a) What is the ratio of the mean density of Mars to that of Earth? (b) What is the value of the gravitational acceleration on Mars...
10. Doubt in resolving forces of a man in an elevator(normal force and weight)

he full acceleration due to gravity with its appropriate sign would be -g. So why are we not using the this? If it were then we would get (-W), and if we plug this value into the equation N-W= ma we would get N-(-W)=ma which would become N+W=ma. My method is to first find why the elevator is...
11. Doubt in resolving forces of a man in an elevator(normal force and weight)

You are saying W=(-9.81m). Right? So now If i plug it into the equatio of N-W=ma won't I end up with N+W=ma ?? And maybe I know this already, but what exactly is the force law?
12. Doubt in resolving forces of a man in an elevator(normal force and weight)

(FYI: g does not have a minus sign!) Why not?? It should, considering gravity is acting downwards!!
13. Doubt in resolving forces of a man in an elevator(normal force and weight)

it is -(m x -g) which will become +mg
14. Doubt in resolving forces of a man in an elevator(normal force and weight)

(Before I start, due to the use of vectors let me state I consider up to be positive and down to be negative) Imagine a scenario, of a man in an elevator. And the elevator is accelerating upwards. Now in this case the Normal force > weight. So Normal Force - Weight =mass X acceleration. If...
15. A thought question on circular motion, of a car travelling in flat road vs banked rod

Well its just a rough variable, think of you driving in a constant circular motion. Once in a flat road and then in a banked road. If you were to keep all variables the same, velocity, road surface, tyre grip etc which terrain would you find easier to maintain the circular motion?