Physics Standard IX, Part 1
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Questions and Answers

Why does the child move his hand backwards along with the ball when catching it?

  • The ball exerts a force on the child's hand pushing it backward. (correct)
  • The child applies an equal and opposite force to stop the ball.
  • To prevent the ball from bouncing back.
  • It is the child's natural reflex to move their hand back.

    • Why does the rope only move in one direction during a tug of war, even though both teams are applying force?

  • The rope is designed to only move in one direction.
  • The force applied by the stronger team overcomes the force applied by the weaker team. (correct)
  • The forces applied by both teams are balanced.
  • The team pulling in the opposite direction is weaker.

    • What is the resultant force if a 100 N force is applied in the east direction and a 150 N force is applied in the west direction?

    50 N towards the west

    The forces acting on a body are said to be balanced forces if the resultant force is zero.

    <p>True</p> Signup and view all the answers

    In the tug of war shown in the figure, is the resultant force experienced on the rope balanced or unbalanced?

    <p>Unbalanced</p> Signup and view all the answers

    All forces cause motion?

    <p>False</p> Signup and view all the answers

    When a vehicle is pushed from ______, it cannot move.

    <p>inside</p> Signup and view all the answers

    What do you observe when a marble is rolled from end A in each situation?

    <p>The marble rolls with increasing speed then decreasing speed.</p> Signup and view all the answers

    Write down a practical definition for inertia.

    <p>The tendency of a body to resist any change in its state of rest or uniform motion.</p> Signup and view all the answers

    What is the tendency of the object to continue in its state of rest or uniform motion?

    <p>Inertia</p> Signup and view all the answers

    What force is required to produce an acceleration of 1 m/s² on an object of mass 1 kg?

    <p>1 Newton</p> Signup and view all the answers

    A body of mass 12 kg is moving with an acceleration of 4 m/s². Calculate the force applied.

    <p>48 N</p> Signup and view all the answers

    A force of 40 N is applied on a body of mass 20 kg. Calculate the acceleration produced.

    <p>2 m/s²</p> Signup and view all the answers

    A vehicle of mass 1000 kg is travelling with a velocity of 90 km/h. The vehicle comes to rest when brakes are applied for 5 s. Calculate the force applied.

    <p>-5000 N</p> Signup and view all the answers

    What does a negative sign for the force typically indicate?

    <p>The force is acting in the opposite direction of motion.</p> Signup and view all the answers

    A shot of mass 7 kg rolled on a level ground, with a velocity 2 m/s, came to rest in 5 s. Which force brought it to rest?

    <p>Friction</p> Signup and view all the answers

    What is the unit of impulse of force?

    <p>Newton-second</p> Signup and view all the answers

    A ball of mass 200 g is moving with a velocity of 30 m/s. A person catches the ball. If the time taken to bring the ball to rest is 0.3 s, what will be the force felt on the arm?

    <p>-200 N</p> Signup and view all the answers

    What does a negative force value indicate in this scenario?

    <p>The arm is pushing back against the ball.</p> Signup and view all the answers

    Why do cricket players move their hands backward along with the ball while catching a fast moving ball?

    <p>To reduce the force exerted on their hands and prevent injury.</p> Signup and view all the answers

    What is the purpose of a foam bed in a pole vault pit?

    <p>To cushion the impact of the vaulter.</p> Signup and view all the answers

    What is the purpose of a sponge or hay placed between glass vessels while packing?

    <p>To cushion the vessels and prevent breakage.</p> Signup and view all the answers

    An object in motion with no force applied will continue in its motion in a straight line or an object at rest will continue in its state of rest.

    <p>True</p> Signup and view all the answers

    What is the force of attraction between two objects of masses m1 and m2, separated by a distance d, according to the Universal Law of Gravitation?

    <p>F = Gm1m2 / d²</p> Signup and view all the answers

    If the distance between the two objects is doubled, what happens to the force of attraction between them?

    <p>It decreases to one-fourth.</p> Signup and view all the answers

    Calculate the gravitational force of attraction between two children of masses 40 kg and 50 kg when they are 2 m apart.

    <p>3.335 × 10⁻⁸ N</p> Signup and view all the answers

    Is Earth the sole contributor to the force of attraction experienced by objects on the planet?

    <p>False</p> Signup and view all the answers

    What is the unit of acceleration due to gravity (g)?

    <p>Meter per second squared</p> Signup and view all the answers

    Which of the following observations is NOT true about acceleration due to gravity (g)?

    <p>It changes with the mass of the object.</p> Signup and view all the answers

    What will be the acceleration of an object at the center of the Earth?

    <p>0 m/s²</p> Signup and view all the answers

    Which region of the Earth is farthest from its center?

    <p>The Equator</p> Signup and view all the answers

    What is the primary reason why objects like leaves or feathers fall slower than objects like rocks or coins in the air?

    <p>Air resistance has a greater effect on them.</p> Signup and view all the answers

    Why does the acceleration of a satellite orbiting the Earth not depend on its mass?

    <p>The gravitational force is constant for all objects at a given distance.</p> Signup and view all the answers

    What is the primary factor that influences the speed of a lander when it reaches the Moon?

    <p>The Moon's gravitational pull.</p> Signup and view all the answers

    Why is it essential to use large rockets to launch satellites into space?

    <p>To overcome the Earth's gravitational pull.</p> Signup and view all the answers

    If an object is lifted from the Earth's surface to a higher altitude, what happens to its mass and weight?

    <p>Mass remains the same, but weight decreases.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a freely falling object?

    <p>It travels at a constant speed.</p> Signup and view all the answers

    Which of the following scenarios does NOT demonstrate weightlessness?

    <p>A swimmer floating in a pool.</p> Signup and view all the answers

    The weight of an object at the Earth's center is zero.

    <p>True</p> Signup and view all the answers

    What is the primary difference between the weight of an object measured on Earth and on the Moon?

    <p>The gravitational force is weaker on the Moon.</p> Signup and view all the answers

    What is the primary reason for the difference in weight between an object measured using a common balance and a spring balance?

    <p>Common balance measures mass, and spring balance measures weight.</p> Signup and view all the answers

    What is the unit of weight?

    <p>Newton</p> Signup and view all the answers

    Which type of motion does a stone tied to a string whirled in a circle exhibit when it covers equal distances in equal intervals of time?

    <p>Uniform circular motion</p> Signup and view all the answers

    What is the acceleration experienced by an object moving in a circular path?

    <p>Centripetal acceleration</p> Signup and view all the answers

    A body can exhibit circular motion without any force acting on it.

    <p>False</p> Signup and view all the answers

    The tendency of a vehicle to roll over while negotiating a curve is due to the centripetal force acting on it.

    <p>True</p> Signup and view all the answers

    What provides the centripetal force for artificial satellites orbiting the Earth?

    <p>Earth's gravitational force.</p> Signup and view all the answers

    Large rockets are extensively used to launch satellites into space to overcome the Earth's gravitational pull.

    <p>True</p> Signup and view all the answers

    What is the primary advantage of using less powerful rockets to launch a spacecraft to the Moon, as demonstrated by Chandrayaan-3?

    <p>It creates a smoother landing on the Moon.</p> Signup and view all the answers

    What is the primary reason for the success of soft landing during lunar missions?

    <p>The gradual reduction of the spacecraft's speed.</p> Signup and view all the answers

    If an object is thrown vertically upward from the surface of the Moon, what will happen to its initial velocity?

    <p>It will gradually decrease.</p> Signup and view all the answers

    What is the primary reason why the Moon's gravitational force affects the Earth, even though the Earth's mass is much larger than the Moon's?

    <p>The Moon is closer to Earth than the Sun.</p> Signup and view all the answers

    Under what condition(s) will a freely falling object experience weightlessness?

    <p>When an object is experiencing freefall and only subjected to Earth's gravity.</p> Signup and view all the answers

    Circular motion is a special case of uniform motion.

    <p>False</p> Signup and view all the answers

    What happens to an object's initial velocity when it is thrown vertically upwards from the Moon's surface?

    <p>It decreases.</p> Signup and view all the answers

    What is the primary force that determines the time it takes for a freely falling object to reach the ground from a specific height?

    <p>The air resistance.</p> Signup and view all the answers

    A stone thrown vertically upwards from the Moon's surface returns to its initial position in 6 seconds.

    <p>True</p> Signup and view all the answers

    A body falls freely from a certain height and takes 50 seconds to reach the ground. How much time will it take to fall from the same height on another sphere having twice the radius and twice the mass of the Earth?

    <p>50√2 seconds</p> Signup and view all the answers

    Why are large rockets required to launch satellites into outer space?

    <p>To overcome Earth's gravitational pull.</p> Signup and view all the answers

    The weight of a satellite in Earth's orbit is the same as its weight on Earth’s surface.

    <p>False</p> Signup and view all the answers

    What is the primary factor that influences the weight of an object on a celestial body?

    <p>The object's distance from the center of the celestial body.</p> Signup and view all the answers

    The weight of an object on the Moon is approximately 1/6th of its weight on Earth.

    <p>True</p> Signup and view all the answers

    Which of the following statements regarding the weight of an object on a celestial body is true?

    <p>The weight of an object is influenced by its mass and the celestial body's gravitational pull.</p> Signup and view all the answers

    The weight of an object is typically measured using a common balance.

    <p>False</p> Signup and view all the answers

    What is the primary reason why a freely falling object experiences weightlessness?

    <p>The object is in a state of freefall and experiences only gravity.</p> Signup and view all the answers

    A skydiver in freefall after deploying the parachute experiences weightlessness.

    <p>False</p> Signup and view all the answers

    What is the speed (approximate) of light in a vacuum?

    <p>3 × 10⁸ m/s</p> Signup and view all the answers

    What is the refractive index of air?

    <p>1</p> Signup and view all the answers

    What is the refractive index of a medium, if the speed of light in that medium is 2 × 10⁸ m/s?

    <p>1.5</p> Signup and view all the answers

    The speed of light is higher in a medium of higher optical density.

    <p>False</p> Signup and view all the answers

    Which of the following options increases the speed of a car?

    <p>Increasing acceleration</p> Signup and view all the answers

    What is the displacement of the child, if it moves from pole B to pole C, then pole D and finally reaches back to pole C?

    <p>40 m</p> Signup and view all the answers

    If a child travels from pole B, reaches pole C and then travels 40 m further in the opposite direction, what will be the possible positions of the child?

    <p>Pole B</p> Signup and view all the answers

    What is the rate of change of velocity called?

    <p>Acceleration</p> Signup and view all the answers

    What is the unit of acceleration?

    <p>m/s²</p> Signup and view all the answers

    A car traveling at** 10 m/s** has an acceleration of 5 m/s². What is the velocity of the car after 2 seconds?

    <p>20 m/s</p> Signup and view all the answers

    If an object starts from rest, it means initial velocity is zero.

    <p>True</p> Signup and view all the answers

    An object moving in the same direction, with equal displacement at equal time intervals is in non-uniform velocity.

    <p>False</p> Signup and view all the answers

    Which of the following options describes uniform velocity?

    <p>The velocity of a train moving at a constant speed in the same direction.</p> Signup and view all the answers

    What is the reason why a bus, initially at rest, will tend to fall backwards when it suddenly moves forward?

    <p>The inertia of rest tends to keep the passengers stationary, while the bus moves forward.</p> Signup and view all the answers

    Why does a coconut fall down from a mango tree when we shake the branch?

    <p>The force applied to the branch is transmitted to the coconut.</p> Signup and view all the answers

    The inertia of an object is directly proportional to its mass.

    <p>True</p> Signup and view all the answers

    If two forces act on an object, one to the ______ and one to the ______ , they are called balanced forces.

    <p>right, left</p> Signup and view all the answers

    What happens to a toy car when equal weights are placed on both ends?

    <p>The toy car will remain stationary due to the balanced force.</p> Signup and view all the answers

    What happens to a toy car moving forward when more weight is added to the pan on the same side?

    <p>The car will speed up because the forces are now unbalanced.</p> Signup and view all the answers

    What happens to the toy car moving forward when more weight is added to the pan on the opposite side?

    <p>The car will move backward.</p> Signup and view all the answers

    A force can be applied to an object from within the object itself.

    <p>False</p> Signup and view all the answers

    A balanced force does not change the state of rest or motion of a body.

    <p>True</p> Signup and view all the answers

    Which of the following options is not correct regarding Galileo's observation about a marble rolling down an inclined plane?

    <p>The constant force exerted by the marble was dependent on the external force.</p> Signup and view all the answers

    According to Newton's First Law of motion, a body will continue to stay in its state of rest or uniform motion if balanced forces are acting on it.

    <p>False</p> Signup and view all the answers

    What is the force responsible for bringing a falling coconut to rest?

    <p>The gravitational force exerted by the Earth.</p> Signup and view all the answers

    If a body of mass 10 kg travels with a speed of 18 m/s from rest at a point, after 2 seconds, what is the rate of change of its momentum (in Newton)?

    <p>30 N</p> Signup and view all the answers

    When a rocket is launched, gases are produced in its chamber due to combustion of fuels, which move in one direction at high speed, While the rocket is propelled in the opposite direction. What is the reason behind this?

    <p>The force exerted by the gases on the rocket is equal and opposite to the force exerted by the rocket on the gases.</p> Signup and view all the answers

    The force exerted by a person on a vehicle is greater than the force exerted by the vehicle on the person.

    <p>False</p> Signup and view all the answers

    The acceleration due to gravity is the same for objects of different masses when those objects fall simultaneously from the same height.

    <p>True</p> Signup and view all the answers

    Why do leaves or feathers fall slowly towards the ground?

    <p>The surface area of these objects is larger, which increases the effect of air resistance.</p> Signup and view all the answers

    The acceleration due to gravity is always the same at every point on the surface of the Earth.

    <p>False</p> Signup and view all the answers

    What is the force exerted by the Earth on 1 kg of mass placed on the surface of the Earth?

    <p>9.8 N</p> Signup and view all the answers

    What is the acceleration of an aeroplane caused by the gravitational force exerted by the Earth, when the aeroplane is 10 km above the surface of the Earth?

    <p>1.6 × 10⁻²⁰ m/s²</p> Signup and view all the answers

    The force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

    <p>True</p> Signup and view all the answers

    The weight of an object is always the same, regardless of its position on the Earth.

    <p>False</p> Signup and view all the answers

    When an object is allowed to fall freely from a height, it will fall to the ground only under the gravitational force of the Earth. This state of motion is called

    <p>Free fall</p> Signup and view all the answers

    A person experiences weightlessness when they are

    <p>Orbiting the Earth in a spaceship</p> Signup and view all the answers

    The weight of an object will be zero when it is falling freely.

    <p>True</p> Signup and view all the answers

    A stone tied to a string is whirled around in a circle. It is in circular motion where the object moves with equal distance at equal intervals of time.

    <p>True</p> Signup and view all the answers

    What is the force responsible for making a stone whirl around in a circle?

    <p>The force exerted by the string.</p> Signup and view all the answers

    In circular motion, the object will move in a straight line if the centripetal force is removed.

    <p>True</p> Signup and view all the answers

    The mass of an object changes as it moves from one place to another.

    <p>False</p> Signup and view all the answers

    The weight of an object changes as it moves from one place to another.

    <p>True</p> Signup and view all the answers

    Which of the following is not an example of circular motion?

    <p>A train running along a railway track with no curves</p> Signup and view all the answers

    Explain why large rockets are needed to launch satellites into space?

    <p>Large rockets are needed to launch satellites into space to overcome the Earth's gravitational pull. The Earth exerts a strong gravitational force on objects near its surface, and it takes considerable energy to overcome this force and propel a satellite into space. Because large rockets are capable of generating significant thrust, they provide the necessary energy to accelerate the satellite to escape velocity, which allows it to break free from the Earth's gravity and enter orbit.</p> Signup and view all the answers

    The mass of an object does not change as it moves from the Earth to the Moon.

    <p>True</p> Signup and view all the answers

    The weight of an object remains the same as it moves from the Earth to the Moon.

    <p>False</p> Signup and view all the answers

    What would be the weight of a 10 kg object on a planet that has twice the mass and three times the radius of the Earth?

    <p>4.44 N</p> Signup and view all the answers

    The acceleration due to gravity, denoted by 'g', is independent of the mass of the object.

    <p>True</p> Signup and view all the answers

    The acceleration due to gravity is the same at all points on the surface of the Earth.

    <p>False</p> Signup and view all the answers

    An object will experience weightlessness when it is falling freely.

    <p>True</p> Signup and view all the answers

    Study Notes

    Physics Standard IX, Part 1

    • This is a textbook for Standard IX Physics, Part 1, prepared by SCERT Kerala, 2024.
    • The book aims to help students understand basic physics concepts, apply them in real-life, and counter superstitions.
    • It includes activities, visuals, and questions to encourage active learning.
    • The book covers topics like Refraction of Light, Equations of Motion, Laws of Motion, and Gravitation.
    • Each section has specific activities and figures for enhanced learning.

    Contents

    • Refraction of Light (page 7)
    • Equations of Motion (page 27)
    • Laws of Motion (page 53)
    • Gravitation (page 73)

    Textbook Development Committee

    • Includes advisors, chairpersons, experts, writers, and artists involved in creating the textbook.
    • Lists specific individuals and their roles in the committee.

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    Physics Standard IX Part 1 PDF

    Description

    Explore the foundational concepts of physics with this SCERT Kerala textbook for Standard IX, Part 1. Delve into important topics such as Refraction of Light, Equations of Motion, Laws of Motion, and Gravitation, along with engaging activities and visuals designed for active learning.

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