Q. Which of the following statements is wrong ?

Gravitation Report Error

A

A ship moving from west to east, along the equator, shall have more less as compared to when it is at rest at the equator

B

A ship moving from east to west, along the equator, shall have more weight as compared to when it is at rest

C

Earth has retained its atmosphere because the value of $\sqrt{\frac{3 k T}{m}}$ for air molecules is larger than escape velocity

D

The time period of a simple pendulum of infinite length is the same as the time period of SHM of a ball in a tunnel along the diameter of earth

Solution:

A ship which moves along the direction of rotation of earth will have more net speed relative to axis of rotation of earth so it will need more centripetal force for its circular motion so the normal reaction on it will be less or its effective weight will be less hence options $(A)$ and (B) are true and option (D) is also true which has time period $2 \pi(R / g)^{1 / 2}$ in both cases. Earth has retained its atmosphere because the value of most probable speed of molecules in atmosphere is less than the escape velocity.

Questions from Gravitation

1. The binding energy of a satellite of mass m in a orbit of radius r is (R = radius of earth, g = acceleration due to gravity)

Maharashtra CET 2005

2. Assertion : Planet is a heavenly body revolving round the sun.
Reason : Star is luminous body made of gaseous material.

AIIMS 2002

3. If $W_1$, $W_2$ and $W_3$ represent the work done in moving a particle from $A$ to $B$ along three different paths $1$, $2$ and $3$ (as shown in fig) in the gravitational field of the point mass $'m'$. Find the correct relation between $'W'_1$, $'W_2'$ and $'W_3'$

Maharashtra CET 2019

4. A projectile is fired from the surface of the Earth of radius $R$ with a velocity $\eta v_{e}$ , where $v_{e}$ is the escape velocity and $\eta < 1$ . Neglecting the air resistance, the orbital velocity of the projectile is

NTA Abhyas 2020

5. The effect of rotation of the Earth on the value of acceleration due to gravity is

NTA Abhyas 2020

Physics Most Viewed Questions

1. If $E$ and $G$ respectively denote energy and gravitational constant, then $\frac{ E }{ G }$ has the dimensions of:

NEET 2021 Physical World, Units and Measurements

2. The de Broglie wavelength of an electron moving with kinetic energy of $144 \,eV$ is nearly

NEET 2020 Dual Nature of Radiation and Matter

3. A car starts from rest and accelerates at $5\, m / s ^{2}$ At $t=4\, s$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t =6\, s$ ? (Take $\left. g =10\, m / s ^{2}\right)$

NEET 2021 Motion in a Straight Line

4. A wheel with $20$ metallic spokes each $1\, m$ long is rotated with a speed of $120\, rpm$ in a plane perpendicular to a magnetic field of $0.4\, G$. The induced emf between the axle and rim of the wheel will be, $(1 G = 10^{-4}\, T)$

NEET 2020 Electromagnetic Induction

5. A barometer is constructed using a liquid (density $= 760 \,kg/m^{3})$ What would be the height of the liquid column, when a mercury barometer reads $76\, cm$ ?
(density of mercury $= 13600 kg/m^{3})$

NEET 2020 Mechanical Properties of Fluids