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Escape velocity of a body from earth is 11.2 \,mathrmkm/s. If the radius of a planet be one-third the radius of earth and mass be one-sixth that of earth, the escape velocity from the planet is:

Solution & Explanation

### Related Formula V_e = sqrtfrac2GMR ### Core Logic For Earth: V_e = sqrtfrac2GM_ER_E = 11.2 mathrm~km/s For the planet: mathrmR_mathrmP = fracmathrmR_mathrmE3 and mathrmM_mathrmP = fracmathrmM_mathrmE6 We can express the escape velocity of the planet V_p as a ratio of the Earth's escape velocity. ### Step 1: Ratio of Velocities fracV_pV_e = sqrtfracM_pM_E times fracR_ER_p fracV_pV_e = sqrtleft(frac16right) times left(frac31right) = sqrtfrac12 ### Step 2: Calculate Escape Velocity V_p = fracV_esqrt2 V_p = frac11.21.414 approx 7.92 mathrm~km/s ### Pattern Recognition Any scaling of a planet's mass by factor alpha and radius by factor beta scales the escape velocity by a factor of sqrtalpha / beta. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Gravitation

Reference Study Guides

More Gravitation Previous-Year Questions — Page 4

Q46 jee_main_2024_31_jan_evening Escape Velocity
The mass of the moon is 1/144 times the mass of a planet and its diameter 1/16 times the diameter of a planet. If the escape velocity on the planet is v, the escape velocity on the moon will be:
  • A. fracv3
  • B. fracv4
  • C. fracv12
  • D. fracv6

Solution

### Related Formula v_textescape = sqrtfrac2GMR ### Core Logic For the planet: v = sqrtfrac2GM_pR_p For the moon: M_m = fracM_p144 and R_m = fracR_p16. ### Step 1: Setup the Ratio v_m = sqrtfrac2G M_mR_m v_m = sqrtfrac2G left(fracM_p144right)left(fracR_p16right) v_m = sqrtfrac2G M_pR_p times frac16144 ### Step 2: Simplification v_m = sqrtfrac2G M_pR_p times sqrtfrac19 v_m = v times frac13 = fracv3 ### Pattern Recognition Escape velocity scales as sqrtM/R. If M scales by x and R scales by y, velocity scales by sqrtx/y. Here, sqrt(1/144)/(1/16) = sqrt16/144 = sqrt1/9 = 1/3. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Gravitation
Q37 jee_main_2024_31_jan_morning Superposition Principle
Four identical particles of mass m are kept at the four corners of a square. If the gravitational force exerted on one of the masses by the other masses is left(frac2sqrt2 + 132right)fracmathrmGm^2mathrmL^2, the length of the sides of the square is
  • A. fracmathrmL2
  • B. 4 L
  • C. 3L
  • D. 2 L

Solution

### Related Formula F = fracG m_1 m_2r^2 ### Core Logic
Superposition Principle diagram for Q37 - JEE Main 2024 Morning
Superposition Principle diagram for Q37 - JEE Main 2024 Morning
Let the side length of the square be a. Considering one corner mass, it experiences forces from the adjacent two masses (distance a) and the diagonally opposite mass (distance sqrt2a). The forces from the two adjacent masses are at 90^circ to each other: F = fracGm^2a^2 The resultant of these two is sqrt2F = sqrt2 fracGm^2a^2, directed along the diagonal. ### Step 2: Total Force Equation The force from the diagonal mass is: F' = fracGm^2(sqrt2a)^2 = fracGm^22a^2 Total resultant force F_textnet = sqrt2F + F': F_textnet = sqrt2 fracGm^2a^2 + fracGm^22a^2 = fracGm^2a^2 left( sqrt2 + frac12 right) F_textnet = fracGm^2a^2 left( frac2sqrt2 + 12 right) Equating this to the given force value: left(frac2sqrt2 + 132right)fracGm^2L^2 = fracGm^2a^2 left( frac2sqrt2 + 12 right) frac132 L^2 = frac12 a^2 a^2 = 16 L^2 a = 4L ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Gravitation

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