Concepts Of Physics MCQ Edition [Volume 1]PhysicsGravitation
Three uniform spheres, each possessing a mass M and a radius a , are positioned such that each one touches the remaining two. Determine the magnitude of the gravitational force exerted on any of the spheres by the other two.
Options
- A2 , GM^2 4a^2
- BGM^2 2a^2
- C3 , GM^2 a^2
- D3 , GM^2 4a^2
Correct answer
D. 3 , GM^2 4a^2
Step-by-step solution
The centers of the three spheres form an equilateral triangle since each sphere touches the other two. The distance between the centers of any two spheres is 2a . The gravitational force exerted by one sphere on another is given by Newton's law of gravitation: F = GM^2 (2a)^2 = GM^2 4a^2 The forces exerted on any one sphere by the other two act along the lines joining their centers, which means the angle between these two forces is 60^ . The magnitude of the resultant gravitational force is: F_ net = F^2 + F^2 + 2F