Download App

PHYSICS [1 Mark Question Answer]

Laws of Motion · ICSE STD 9 (ICSE - English Medium). 39 questions.

Questions

[1 Mark Question Answer]

🎯

Test yourself on this topic

39 questions · timed · auto-graded

Question 11 Mark
What do you understand by the term force due to gravity ?
Answer
The force with which the Earth attracts a body towards its centre is called the force due to gravity.
View full question & answer→
Question 21 Mark
Write the numerical value of gravitational constant $G$ with its $S.I.$ unit .
Answer
The value of $G$ in the $S.I.$ system is $6.67 \times 10^{-11}\ Nm^2\ kg^{-2}.$
View full question & answer→
Question 31 Mark
Define gravitational constant G.
Answer
The gravitational constant is defined as the force of attraction between two bodies of unit mass separated by a unit distance .
View full question & answer→
Question 41 Mark
How is the gravitational force between two masses affected if the separation between them is doubled?
Answer
$F \propto \frac{ Gm _1 m _2}{ d ^2}$ If the distance between the masses becomes half, the force reduces to one-fourth.
View full question & answer→
Question 51 Mark
How does the gravitational force of attraction between two masses depend on the distance between them?
Answer
The gravitational force of attraction between two masses is inversely proportional to the square of distance between them.
View full question & answer→
Question 61 Mark
State whether the gravitational force between two masses is attractive or repulsive ?
Answer
Gravitational force is always attractive .
View full question & answer→
Question 71 Mark
Explain the meaning of the following statement $'1\ kgf = 9.8\ N'.$
Answer
$1\ kgf = 9.8\ N.$ One kilogramme force is the force due to gravity on a mass of $1$ kilogramme.
View full question & answer→
Question 81 Mark
Which of the following quantity does not change by change of place of a body : mass or weight ?
Answer
Mass of a body is always constant.
View full question & answer→
Question 91 Mark
State the $S.I.$ units of $(a)$ mass and $(b)$ weight.
Answer
The $S.I.$ unit of mass is kg and that of weight is newton.
View full question & answer→
Question 101 Mark
How are $g$ and $G$ realated $?$
Answer
Acceleration due to gravity $(g)$ is directly proportional to universal gravitational constant $(G).$
View full question & answer→
Question 111 Mark
How is the acccelaration due to gravity on the surface of the earth realted to its mass and radius ?
Answer
Let $g$ be the acceleration due to gravity on the Earth's surface $($mass $= M$ and radius $= R).$ Then , $g =\frac{ Gm }{ R ^2}$
View full question & answer→
Question 121 Mark
Write down the average value of $g$ on Earth's surface $?$
Answer
The average value of $'g'$ on the Earth's surface is $9.8\ m/s^2.$
View full question & answer→
Question 131 Mark
Define the term acceleration due to gravity? Write its $S.I.$ unit.
Answer
The rate at which the velocity of a freely falling body increases is called acceleration due to gravity. Its $S.I.$ unit is $ m/s^2.$
View full question & answer→
Question 141 Mark
Name and state the action and reaction in the following case : A moving train colliding with a stationary train
Answer
Action: Force exerted by a moving train on a stationary train. Reaction: Force exerted by a stationary train on a moving train.
View full question & answer→
Question 151 Mark
Name and state the action and reaction in the following case : A person moving on the floor
Answer
Action: Force exerted by the feet on the ground in backward direction. Reaction: Force exerted by the ground on feet in forward direction.
View full question & answer→
Question 161 Mark
Name and state the action and reaction in the following case : A moving rocket
Answer
Action: Force exerted by the rocket on the gases backwards. Reaction: Force exerted by outgoing gases on the rocket in forward direction.
View full question & answer→
Question 171 Mark
Name and state the action and reaction in the following case : A book lying on a table
Answer
Action: Weight of the book acting downwards. Reaction: Force acted by the table upwards.
View full question & answer→
Question 181 Mark
Name and state the action and reaction in the following case :
Hammering a nail
Answer
Action: The force exerted by the hammer on the nail. Reaction: The force applied by the nail on the hammer.
View full question & answer→
Question 191 Mark
Name and state the action and reaction in the following case : Firing a bullet from a gun
Answer
Action: Force exerted on the bullet. Reaction: Recoil experienced by the gun.
View full question & answer→
Question 201 Mark
A boy pushes a wall with a force of $10\ N$ towards east. What force is exerted by the wall on the boy?
Answer
The wall exerts an equal force of $10\ N$ on the boy in the opposite direction, i.e. west.
View full question & answer→
Question 211 Mark
State the usefulness of Newton's third law of motion .
Answer
Newton's third law explains how a force acts on an object.
View full question & answer→
Question 221 Mark

The 'Action and reaction are equal in magnitude'. Is this statement true?

Answer
Yes, action and reaction are equal in magnitude.
View full question & answer→
Question 231 Mark

The action and reaction both act simultaneously. Is this statement true?

Answer
Yes, action and reaction act simultaneously.
View full question & answer→
Question 241 Mark
A person pushing a wall hard is liable to fall back. Give reason.
Answer
A person pushing a wall hard $($action$)$ by his palm, experiences a force $($reaction$)$ exerted by the wall on his palm in the opposite direction; thus, he is liable to fall backwards.
View full question & answer→
Question 251 Mark
Define linear momentum and state its $S.I.$ unit.
Answer
Linear momentum of a body is the product of its mass and velocity. Its $SI$ unit is $kg\ ms^{-1}.$
View full question & answer→
Question 261 Mark
Name the two factors on which the force needed to stop a moving body in a given time depends.
Answer
Force needed to stop a moving body in a given time depends on its mass and velocity.
View full question & answer→
Question 271 Mark
Give qualitative definition of force on the basic of Newton's first law of motion.
Answer
Force is that external cause which can move a stationary object or which can stop a moving object.
View full question & answer→
Question 281 Mark

What is meant by the term inertia?

Answer
The property of an object by virtue of which it neither changes its state nor tends to change the state is called inertia.
View full question & answer→
Question 291 Mark
What is Galileo's law of inertia?
Answer
Galileo's law of inertia states that a body continues to be in its state of rest or of uniform motion unless an external force is applied on it.
View full question & answer→
Question 301 Mark
A ball is moving on a perfectly smooth horizontal surface. If no force is applied on it, then will its speed decrease, increase or remain unchanged?
Answer
In absence of any external force , its speed shall remain unchanged .
View full question & answer→
Question 311 Mark
A ball moving on a table top eventually stops. Explain the reason .
Answer
The force of friction between the table and the ball opposes the motion of the ball.
View full question & answer→
Question 321 Mark
Is force needed to keep a moving body in motion?
Answer
Force is not needed to keep a moving body in motion.
View full question & answer→
Question 331 Mark
Explain the following :
It is advantageous to run before taking a long jump .
Answer
When running, the athlete brings his body in the state of motion. When the body is in motion, it becomes easier to take a long jump.
View full question & answer→
Question 351 Mark
An aeroplane is moving uniformly at a constant height under the action of two forces $(i)$ Upward force $($lift$)$ and $(ii)$ Downward force $($weight$).$ What is the net force on the aeroplane$?$
Answer
The net force on the airplane is zero or the upward force is equal to the downward force.
View full question & answer→
Question 361 Mark

Two equal and opposite forces act on a moving object. How is its motion affected? Give reason.

Answer
The motion remains unaffected because the net force acting on it is zero.
View full question & answer→
Question 371 Mark
Two equal and opposite forces act on a stationary body. Will the body move? Give a reason to your answer.
Answer
No, the body will not move because the net force acting on it is zero. Hence, it will remain stationary due to inertia of rest.
View full question & answer→
Question 381 Mark
'More the mass, the more difficult it is to move the body from rest'. Explain this statement by giving an example.
Answer
It is difficult, i.e. a larger force is required to set a loaded trolley $($which has more mass$)$ in motion than an unloaded trolley (which has less mass).
View full question & answer→
Question 391 Mark
Name the factor on which the inertia of a body depends and state how does it depend on the factor stated by you .
Answer
Inertia of a body depends on its mass. Inertia is directly proportional to mass, i.e. greater the mass of a body, greater is its inertia.
View full question & answer→
Generate Paper FreeAll Laws of Motion topics
[1 Mark Question Answer] - PHYSICS STD 9 Questions - Vidyadip