Physics circular motion, orbits, and gravity

In summary, Bert and Ernie are stationary at different distances from a star named Alpha Sesame. Big Bird, who has the same mass as the twins, orbits the star in a spaceship. Answers to the given questions are as follows: 1) True, 2) True, 3) True, 4) False, and 5) False. The relation between the distances and gravitational force is squared, making Bert's gravitational force 9 times greater than Ernie's.
  • #1
thesandalman
11
0

Homework Statement



ics
Consider identical twins named Bert and Ernie who are visiting a star named Alpha Sesame. Bert is at a distance r from the star while Ernie is located a distance 3r. Both Bert and Ernie are stationary (they are standing on platforms built by an alien super race) and are not orbiting the star. Big Bird, who has the same mass as Bert and Ernie despite his larger volume, flies by Bert in a spaceship which is in a circular orbit or radius r around Alpha Sesame.

All Answers are true or false:

-If Bert and Ernie would step on bathroom scales, Bert's weight would be 9 times larger than Ernie's.
-If Bert were to step off the platform and fall toward the star, he would experience an identical acceleration to that of Big Bird.
-If Big Bird were to step on a bathroom scale in the spaceship, the scale would register zero.
-Big Bird's acceleration is zero.
-The gravitational force that Bert feels is 3 times larger than the gravitational force Ernie feels.



Homework Equations






The Attempt at a Solution



I know the third answer to be true. I believe the fourth question is false due to gravity. Not so sure about the other ones. That is where I need the help!
 
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  • #2
For this question you need to look at Newton's law of universal gravitation,
F=(Gm1m2)/r^2. Also, take a look at centripetal force, F=(m*V^2)/R.
That should get you started.
 
  • #3
Ok, here is what I am thinking:
Question 1 is true due to the fact that force is 1/9 or therefore 9 times the weight. Question 2 i also say is true because the same force would be acting on both big bird in orbit and Burt when he falls off the platform.
Question 3 I know is true because they are in the equlibrium.
Question 4 is False due to gravity.
Question 5 is true due to this equation F=(Gm1m2)/r^2.

Am I on the right track?
 
  • #4
I agree with your answer for question number one, since the relation between the distances is squared. Question two seems ok also. I don’t understand question 3.
Number four is correct there is an acceleration. I don’t agree with number 5 because if you look at F=(Gm1m2)/r^2, Bert feels a gravitational force 9 times greater, the term in r^2.
 
  • #5
Thanks you so very much for your help! I really appreciate it! You were correct by the way.
 

1. What is circular motion?

Circular motion is the movement of an object along a circular path. This type of motion requires a centripetal force to continuously pull the object towards the center of the circle, causing it to change direction.

2. How are circular orbits related to gravity?

Circular orbits are a result of the gravitational force between two objects. The force of gravity between the two objects keeps them in a circular path around each other, creating a stable orbit.

3. What is the difference between circular and elliptical orbits?

Circular orbits have a constant radius and are symmetrical, while elliptical orbits have varying radii and are asymmetrical. Additionally, elliptical orbits have two focal points, while circular orbits only have one.

4. How does the mass of an object affect its orbit?

The mass of an object has a direct effect on its orbit. The greater the mass, the greater the gravitational force, which leads to a stronger pull towards the center of the orbit. This results in a smaller radius and a faster speed for the object.

5. What is the role of inertia in circular motion?

Inertia is the tendency of an object to resist any change in its motion. In circular motion, inertia plays a role in keeping the object moving along the circular path, as it tries to maintain its velocity in a straight line. This is why a centripetal force is necessary to continuously change the object's direction.

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