back to directory
NEET PHYSICSGRAVITATIONMedium

Question

Two spherical bodies of masses M and 5M and radii R and 2R are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is:

A

2.5 R

B

4.5 R

C

7.5 R

D

1.5 R

Step-by-Step Solution

Since the system consists of two bodies attracting each other under mutual gravitational force, there is no external force acting on the system (Fext=0F_{ext} = 0). Therefore, the position of the centre of mass remains stationary.

The initial distance between the centres is 12R12R. Collision occurs when the bodies touch, meaning the distance between their centres becomes the sum of their radii: R+2R=3RR + 2R = 3R. The total distance covered by both bodies is dtotal=Initial SeparationFinal Separation=12R3R=9Rd_{total} = \text{Initial Separation} - \text{Final Separation} = 12R - 3R = 9R.

Since the centre of mass is stationary, the distance moved by each body is inversely proportional to its mass (m1d1=m2d2m_1 d_1 = m_2 d_2). Let d1d_1 be the distance moved by the smaller mass MM and d2d_2 be the distance moved by the larger mass 5M5M. d1=m2m1+m2×dtotald_1 = \frac{m_2}{m_1 + m_2} \times d_{total} Substituting the values: d1=5MM+5M×9R=56×9R=7.5Rd_1 = \frac{5M}{M + 5M} \times 9R = \frac{5}{6} \times 9R = 7.5 R.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from GRAVITATION. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSGRAVITATIONsphericalbodiesmassesreleasedinitial

More GRAVITATION Questions

View all

The radii of the circular orbits of two satellites A and B of the earth are 4R and R, respectively. If the speed of the satellite A is 3v, then the speed of the satellite B will be:

A.3v/4
B.6v
C.12v
D.3v/2
EasySolve

A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximate radius would earth (mass = 5.98 × 10²⁴ kg) have to be compressed to be a black hole?

A.10⁻⁹ m
B.10⁻⁶ m
C.10⁻² m
D.100 m
MediumSolve

A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest:

A.at the instant just before the body hits the earth
B.it remains constant all through
C.at the instant just after the body is projected
D.at the highest position of the body
MediumSolve

The figure shows elliptical orbit of a planet m about the sun S. The shaded area SCD is twice the shaded area SAB. If $t_1$ is the time for planet to move from C to D and $t_2$ is the time to move from A to B, then:

A.$t_1 > t_2$
B.$t_1 = 4t_2$
C.$t_1 = 2t_2$
D.$t_1 = t_2$
EasySolve

If the mass of the sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following statements would not be correct?

A.Raindrops would drop faster.
B.Walking on the ground would become more difficult.
C.Time period of a simple pendulum on the earth would decrease.
D.Acceleration due to gravity (g) on earth would not change.
MediumSolve

The kinetic energies of a planet in an elliptical orbit around the Sun, at positions A, B and C are $K_A$, $K_B$ and $K_C$ respectively. AC is the major axis and SB is perpendicular to AC at the position of the Sun S, as shown in the figure. Then:

A.$K_A > K_B > K_C$
B.$K_B > K_A > K_C$
C.$K_A < K_B < K_C$
D.$K_B < K_A < K_C$
EasySolve

At what height from the surface of the earth, are the gravitation potential and the value of $g$ are: $-5.4 \times 10^7 \text{ J/kg}$ and $6.0 \text{ ms}^{-2}$ respectively? (Take, the radius of the earth as $6400 \text{ km}$)

A.1600 km
B.1400 km
C.2000 km
D.2600 km
MediumSolve

A particle is released from a height $S$ above the surface of the earth. At a certain height, its kinetic energy is three times its potential energy. The height from the earth's surface and the speed of the particle at that instant are respectively:

A.$\frac{S}{2}, \frac{\sqrt{3gS}}{2}$
B.$\frac{S}{4}, \sqrt{\frac{3gS}{2}}$
C.$\frac{S}{4}, \frac{3gS}{2}$
D.$\frac{S}{4}, \frac{\sqrt{3gS}}{3}$
MediumSolve

This neet physics practice question is part of the TopperSquare free question bank. TopperSquare offers 15,000+ chapter-wise NEET MCQs across Physics, Chemistry, and Biology with detailed step-by-step explanations, full mock tests, NEET PYQs (2010–2024), and an AI-powered performance analytics dashboard. browse all neet practice questions → · practice physics sets →