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Physics 1 Marks Question

Gravitation · MP Board (MPBSE) STD 11 Science (Madhya Pradesh - English Medium). 128 questions.

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Question 11 Mark
Choose the correct alternative: The formula $-\text{G Mm}\Big(\frac{1}{\text{r}_2}-\frac{1}{\text{r}_1}\Big)$ is more/ less accurate than the formula mg(${\text{r}_2}$ - ${\text{r}_1}$) for the difference of potential energy between two points ${\text{r}_2}$ and ${\text{r}_1}$ distance away from the centre of the earth.
Answer
More.
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Question 21 Mark
A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant (a) linear speed, (b) angular speed, (c) angular momentum, (d) kinetic energy, (e) potential energy, (f) total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the Sun.
Answer
A comet while going on elliptical orbit around the Sun has constant angular momentum and total energy at all locations but other quantities vary with locations.
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Question 31 Mark
Choose the correct alternative: Acceleration due to gravity increases/ decreases with increasing altitude.
Answer
Decreases.
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Question 41 Mark
Choose the correct alternative: Acceleration due to gravity is independent of mass of the earth/ mass of the body.
Answer
Mass of the body.
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Question 51 Mark
Choose the correct alternative: Acceleration due to gravity increases/ decreases with increasing depth (assume the earth to be a sphere of uniform density).
Answer
Decreases.
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Question 71 Mark
Should the value of escape velocity be less or more on the surface of Moon as compared to Earth?
Answer
Since, escape velocity, $\text{v}_\text{e}=\sqrt{2\text{gR}}$The value of 'g' and 'R' is less on Moon than the corresponding values on Earth, therefore, value of escape velocity at Moon surface is less.
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Question 91 Mark
Choose the correct alternative: The formula $-\text{G Mm}\Big(\frac{1}{\text{r}_2}-\frac{1}{\text{r}_1}\Big)$ is more/ less accurate than the formula mg(${\text{r}_2}$ - ${\text{r}_1}$) for the difference of potential energy between two points ${\text{r}_2}$ and ${\text{r}_1}$ distance away from the centre of the earth.
Answer
More.
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Question 101 Mark
An artificial satellite is at a height of 36,500km above earth's surface. What is the work done by earth's gravitational force in keeping it in its orbit?
Answer
Zero.
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Question 131 Mark
When a pendulum clock is taken to a mountain, it becomes slow. But a wrist watch controlled by a spring remains unaffected. Explain.
Answer
At the mountain, g decreases and time period of the pendulum clock increases at $\text{T}=2\pi\sqrt{\frac{\text{l}}{\text{g}}}.$ On the other hand, a spring in the wrist watch remains unaffected by the variation of g.
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Question 151 Mark
Acceleration due to gravity decreases more rapidly _________ earth surface.
Answer
Acceleration due to gravity decreases more rapidly above earth surface.
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Question 161 Mark
How earth retains most of the atmosphere?
Answer
Earth retains most of the atmosphere due to force of gravity.
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Question 171 Mark
Do the force of friction and other contact forces arise due to gravitational attraction? If not, then what is the origin of these forces?
Answer
Contact forces have electrical region.
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Question 181 Mark
What would happen if the force of gravity were to disappear suddenly?
Answer
The universe would collapse. We would be thrown away because of the centrifugal force. Eating, drinking and infact all activities would become impossible.
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Question 191 Mark
Would we have more sugar to the kilogram at the pole or at the equator?
Answer
$\text{mg}_\text{P}=\text{m}'\text{g}_\text{e}$ since, $\text{g}_\text{P}>\text{g}_\text{e},$ $\therefore$ m' > m. So, we shall have greater mass of sugar at the equator.
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Question 201 Mark
Does the speed increase, decrease or remain constant when a planet comes closer to the sun?
Answer
The speed of the planet increases when it comes closer to the sun.
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Question 211 Mark
The force of attraction between earth and any object lying on or near its surface is known as ­­__________.
Answer
The force of attraction between earth and any object lying on or near its surface is known as ­­gravity.
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Question 221 Mark
Is it possible to put an artificial satellite in an orbit such a way that it always remains visible directly over New Delhi?
Answer
It is not possible. This is because New Delhi is not in the equatorial plane.
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Question 231 Mark
Give a method for the determination of the mass of the moon.
Answer
By making use of the relation, $\text{g}_\text{m}=\frac{\text{GM}_\text{m}}{\text{R}^2_\text{m}}$
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Question 241 Mark
What is the angle between the equatorial plane and the orbital plane of Polar satel lite?
Answer
The polar satellite revolves along North to South pole. So its plane makes 90 0 with equatorial plane.
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Question 251 Mark
If a satellite is revolving around a planet of density $\rho,$ show that the entity $\rho\text{T}^2$ is a universal constant. When a satellite is orbiting close to earth, then.
Answer
$\frac{\text{GMm}}{\text{R}^2}=\text{mR}\omega^2$$\frac{\text{G}\frac{4}{3}\pi\text{R}^3\rho\text{m}}{\text{R}^2}=\text{m R}\frac{4\pi^2}{\text{T}^2}$
$\rho\text{T}^2=\frac{3\pi}{\text{G}}=\text{a constant}.$
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Question 261 Mark
An artificial satellite revolving around the earth does not need any fuel. On the other hand, the aeroplane requires fuel to fly at a certain height.Why?
Answer
The satellite move in air-free region, while the aeroplane has to overcome air resistance.
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Question 271 Mark
What is the weight of a body in a geostationary satellite?
Answer
The weight of a body is zero in a geostationary satellite.
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Question 281 Mark
Are the Kepler's laws applicable only to the solar system?
Answer
No, they are applicable to the artificial satellites too.
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Question 291 Mark
Does the force of attraction between two bodies depend upon the presence of other bodies and properties of intervening medium?
Answer
No, since it acts along the line joining them and is a central force.
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Question 301 Mark
Is gravitational potential a scalar or a vector? Why?
Answer
Gravitational potential at a point is a scalar quantity because it is defined as work done per unit mass and the work done is a scalar quantity.
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Question 311 Mark
Is it possible to put a satellite into its orbit by firing it from a huge sized gun?
Answer
Theoretically, it is possible but practically it is not feasible on account of large air resistance and other technical difficulties.
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Question 321 Mark
Name one factor on which the period of revolution of a planet around the Sun depends.
Answer
Period of revolution of a planet around the Sun depends upon the distance of the planet from the Sun (i.e., orbital radius of the planet).
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Question 341 Mark
Time period of geostationary satellite around earth is _________.
Answer
Time period of geostationary satellite around earth is 24 hours.
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Question 351 Mark
A mass M is broken into two parts: m and (M - m). How is m related to M so that the gravitational force between two parts is maximum?
Answer
The gravitational force will be maximum when m (M - m) is maximum i.e., when m = M - m 2m = M $\Rightarrow\ \text{m}=\frac{\text{M}}{2}.$
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Question 361 Mark
From where does a satellite revolving around a planet get the required centripetal force?
Answer
From gravitational attraction of planet exerted on satellite.
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Question 371 Mark
The masses of two bodies are doubled and the distance is halved, how will the gravitational force change?
Answer
Since $\text{F}\propto\frac{\text{m}_1\text{m}_2}{\text{r}^2}$ Thus gravitational force will be 8 times more.
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Question 381 Mark
Gravitational force of attraction between two bodies of unit mass placed at unit distance apart is known as _________.
Answer
Gravitational force of attraction between two bodies of unit mass placed at unit distance apart is known as universal gravitational constant.
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Question 391 Mark
Why does tides arise in the oceans?
Answer
Tides arise in the oceans due to the force of attraction between the moon and sea water.
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Question 401 Mark
Give the S.I. units of 'g' and 'G'.
Answer
The S.I. units of ' g ' is $\mathrm{ms}^{-2}$ and the S.I. units of ' G ' is $\mathrm{Nm}^2 / \mathrm{kg}^2$.
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Question 411 Mark
The mass of two bodies are doubled and the distance is halved, how will the gravitational force change?
Answer
Since $\text{F}\propto\frac{\text{m}_1\text{m}_2}{\text{r}^2}$ force will be 16 times more.
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Question 421 Mark
If earth be at one half its present distance from the sun, then how many days will there be in a year?
Answer
According to Kepler's third law, $\text{T}^2\propto\text{R}^3$ Hence, $\frac{\text{T}_1^2}{\text{T}^2_2}=\frac{\text{R}^3_1}{\text{R}^3_2}$ $\Rightarrow\text{T}^2_2=\Big[\frac{\text{R}_2}{\text{R}_1}\Big]^3\text{T}^2_1$ $\Rightarrow\text{T}_2=\text{T}_1\Big[\frac{\text{R}_2}{\text{R}_1}\Big]^{\frac32}=365\bigg(\frac{\frac{\text{R}}{2}}{\text{R}}\bigg)^{\frac32}$ $=365\times\frac{1}{2\sqrt2}=129\text{day}s$
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Question 431 Mark
If suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, then what will happen to the satellite?
Answer
If suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, satellite will not be able to revolve around the earth. Instead, the satellite will start moving along a straight line tangentially at that point on its orbit, where it is at the time of gravitational force becoming zero.
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Question 441 Mark
How much energy is required by a satellite to keep it orbiting? Neglect air resistance.
Answer
No energy is required. This is because the work done by centripetal force is zero.
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Question 451 Mark
Can we determine the gravitational mass of a body inside on artificial satellite?
Answer
No, artificial satellite is like a freely falling body and the weight of the body inside the satellite is zero.
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Question 461 Mark
Why does a person in a satellite feels weightlessness?
Answer
Since no reaction is experienced by the person, he feels weightlessness.
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Question 471 Mark
Two artificial satellites, one close to the surface and other away are revolving around the earth. Which of them has larger speed?
Answer
Both have same speed of gR.
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Question 481 Mark
What is the reason for absence of atmosphere in some planets?
Answer
Very less escape velocity of 2.38km/sec.
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Question 491 Mark
Two satellites of masses 3m and m orbit the earth in circular orbits of radii r and 3r respectively. What is the ratio of their orbital speeds?
Answer
Since, $\text{v}=\sqrt{\frac{\text{GM}}{\text{r}}}$ i.e., $\text{v}\propto\frac{1}{\sqrt{\text{r}}}$ Thus, $\frac{\text{v}_1}{\text{v}_2}=\sqrt{\frac{\text{r}_2}{\text{r}_1}}$ $=\sqrt{\frac{3\text{r}}{\text{r}}}=\sqrt{3}$
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Question 501 Mark
The square of the period of revolution of a planet around the sun is proportional to the ________ of the semimajor axis of its elliptical orbit.
Answer
The square of the period of revolution of a planet around the sun is proportional to the cube of the semimajor axis of its elliptical orbit.
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1 Marks Question - Physics STD 11 Science Questions - Vidyadip