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- Choose the most appropriate answer.
- Which of the following has the least inertia?
pencil b. School bag c.Book d. TableAns. Pencil because it has less mass. - If A and B are two objects with masses 6 kg and 34 kg respectively then,
A has more inertia than B b. B has more inertia than A
c. A and B have the same inertia c. none of the two has inertiaAns. B has more inertia than A because B has more mass than A - Newton’s first law of motion is also called the
law of momentum b. law of mements
c. law of inertia (ans) d. law of mases - A passenger in a bus tends to fall backward when the bus starts suddenly due to the
inertia of rest (ans) b. inertia of motion
c. inertia of direction d. none of these - A cyclist does not come to rest immediately after he stops paddling due to the
inertia of rest b. inertia of motion (ans)
c. inertia of direction d. none of these - Answer these questions
- State Newton’s first law of motion.
Ans: Newton’s first law of motion states that “Every body continues to be in its state of rest or of uniform motion in a straight line unless it is compelled by some external force to change that state. - Explain with an example that a body at rest will remain at rest unless some external force acts upon it to change its state of rest.
Ans: We observe in our daily life that an object lying anywhere keeps on lying there only unless someone moves it from there. For example a chair, a table, a bed etc. - Exaplin with an example that body continues to move along the same straight line unless some external force acts upon it to change its direction of motion.
Ans: A cyclist riding along a road does not come to rest immediately after he stops paddling. The bicycle continues after he stops paddling. The bicycle continues to move forward due to the inertia of motion. But eventually it comes to rest as a result of the retarding action of motion. - Define inertia on the basis of Newton’s first law of motion. Give a suitable example also.
Ans: A body on its own cannot change its state of rest or state of uniform motion alonf a straight line. This inability of a body to change by itself its state of rest or of uniform motion along a straight line is called inertia of the body.
Given below is a simple example to demonstrate the property of inertia.
Take an empty and dry glass tumbler. Place a square piece of thick, smooth card over the mouth of the glass. Place a coin at the center of the card.
b. now, flick the card horizontally striking it hard with your finger. The card piece flies away and the coin falls into the glass.
Explanation : Initially both the card and coin are at rest. When the card is flicked, it comes into motion. The coin, however, remains at rest due to the inertia of rest. As a result, only the card flies away and the coin falls into the glass tumbler. - Establish the relationship between mass and inertia. Give an example.
A heavier body has more inertia than a lighter body. Therefore we can say that ‘more the mass, more is the inertia and lesser the mass, lesser is the inertia of a body’. For example a large and heavy trolley shows a greater resistance to change its state of rest or of uniform motion than a small and lighter object like a toy car. - Give two examples to show that greater the mass, greater is the inertia of the body.
Example-1. Mass of a train is more than the mass of a bicycle. So train has the more inertia than a bicycle.
Example-2. A toy car has less mass than an original car so the toy car has less inertia than an original car. - Write an experiment to demonstrate the property of inertia.
Given below is a simple experiment to demonstrate the property of inertia.
a. Take an empty and dry glass tumbler. Place a square piece of thick, smooth card over the mouth of the glass. Place a coin at the center of the card.
b. now, flick the card horizontally striking it hard with your finger. The card piece flies away and the coin falls into the glass.
Explanation : Initially both the card and coin are at rest. When the card is flicked, it comes into motion. The coin, however, remains at rest due to the inertia of rest. As a result, only the card flies away and the coin falls into the glass tumbler. - Define the term the inertia of rest.
A body at rest remains at rest and cannot start moving on its own. This inherent property of body to resist any change in its state of rest is called inertia of rest. - Explain the following by giving suitable reasons:
- A passenger in a bus tends to fall backward when it starts suddenly.
When the bus starts suddenly, the lower part of the passenger’s body starts moving forward with the bus. But the upper part of the body tends to remain in the state of rest due to inertia of rest. As a result, the passenger falls backward.
- A passenger in a bus tends to fall backward when it starts suddenly.
- State Newton’s first law of motion.
- Dust can be removed from a hanging carpet by shaking it or by beating it with a stick.
Ans: Both the carpet and the dust are at rest. When the carpet is shaken or beaten with a stick, the carpet is set into motion while the dust remains in the state of rest due to inertia of rest. Thus the dust comes out side and falls down due to the pull of gravity. - A bullet fired against a glass window pane makes a hole in it without cracking it.
Ans: Initially the entire glass is in the state of rest. When a bullet strikes a glass plane, the part of the glass pane which comes in contact with the bullet immediately shares the large velocity of the bullet and flies away making a hole. The remaining part of the glass, due to inertia of rest, remains at rest and is not cracked. - A passenger in a moving bus tends to fall backward when it stops suddenly.
Ans: When the bus stops suddenly, the lower part of the passenger’s body comes to rest along with the bus. The upper part of his body tends to remain in the state of motion due to it’s inertia of motion. As a result the passenger leans forward. - A person jumping out of a speeding bus may get seriously injured.
Ans: When the passenger jumps out of a speeding bus, the lower part of the person’s body comes to rest on touching the ground. The upper part of his body tends to remain in the state of motion due to its inertia of motion. As a result, the person jumping out of the speeding bus falls forward and get seriously injured. - An athlete runs a certain distance before taking a long jump.
Ans:The velocity acquired by running is added to the velocity of the athlete at the time of jump. Hence. He can jump over a longer distance due to increased inertia of motion.