General Q&A for Class 12 · Page 73
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
What is meant by positive work, negative work and zero work? Give one example of each work?
Positive work: If the force and displacement are in the same direction. Example: When a body of mass m falls vertically downwards through a height h under gravity. Work done by gravity is positive. Zero work: Force and displacement are at right angle to each other. Example: When a person holding a suitcase on his head moves on a horizontal road. Work done by gravity is zero. <
- GeneralClass 12All
Why the work done by centripetal force is zero?
Because centripetal force is perpendicular to the displacement of the body.
- GeneralClass 12All
Two stones of different sizes are dropped simultaneously from the top of a building. Which stone will reach earlier?
Both the stones reach the ground simultaneously.
- GeneralClass 12All
Why does a cyclist lean to one side, while going along a curve? In what direction does he lean?
A component of normal reaction of the ground provide him the centripetal force, he requires for tuning towards the centre of the circular path. Inside the circle.
- GeneralClass 12All
In a two dimension motion why normal acceleration cannot change the magnitude of velocity?
Normal acceleration is at π/2 with velocity hence cannot change the magnitude.
- GeneralClass 12All
What is the difference between uniform and Non-uniform circular motion?
When a particle moves on a circular path in such a way that its angular speed is constant, it is said to be in uniform circular motion whereas in non-uniform circular motion angular speed of the particle is not constant.
- GeneralClass 12All
Why hydrostatic pressure is a scalar quantity even though pressure is force divided by area, and force is a vector?
Since hydrostatic pressure is transmitted equally in all directions therefore we cannot associate direction with pressure. So, hydrostatic pressure is a scalar quantity.
- GeneralClass 12All
A particle is moving in such a way that its average speed is equal to the magnitude of its average velocity. Predict about the motion of particle A.
Particle is moving in a straight line in same direction throughout the motion.
- GeneralClass 12All
Define displacement of a particle.
The change in position co-ordinates of a particle over a given period of time is called the displacement of the particle
- GeneralClass 12All
Give an example where the rate of change of velocity is constant, while the velocity it self changes both in magnitude and direction
Projectile motion.
- GeneralClass 12All
The length of a rectangular piece of sheet metal is measured with a wooden ruler to be 12 mm. The width of the rectangular piece is measured using a micrometer callipers and found to be 5.98 mm. Give your answers to the following questions to the correct number of significant numbers. (a) what is the area of the rectangle? (b) what is the difference between length and breadth?
(a) Area = Length × Breadth = 12 mm × 5.98 mm = 71.76 mm2 = 72 mm2 (b) Difference = Length – Breadth = 12 mm – 5.98 mm = 6.02 = 6 mm
- GeneralClass 12All
State two important limitations of dimensional analysis.
Limitations of dimensional analysis (i) It cannot give the value of dimensionless constant . (ii) It cannot predict whether a dimensionally correct equation is physically correct or not.
- GeneralClass 12All
If you were a baby crocodile, would you tell Makara that he was wrong? What would you say to convince him?
As a baby crocodile, I would certainly tell Makara that he was wrong. The elders can be frightened into silence more easily as Makara did in his meetings. It is, however, not so easy to shout at a baby. It si because this lets a person down in the public image. To convince makara that he was wrong, I would make three important points. First, it is the duty of the strong ot protect the weak and not to torture them. Secondly, a strong animal is strong only when there are the weak. Elimi
- GeneralClass 12All
In what way is Pambupatti different form any other village?
Unlike other villages, people of Pambupatti lived in peace. They did not fight in the name of religion or language.
- GeneralClass 12All
Do you agree that it is difficult not ot go along with someone who is very strong and powerful? Express your views frankly and clearly.
Of course, it is difficult not to go along with someone who is very strong and powerful. It is human nature to be on the safe side. Disagreeing with a powerful person is likely to call for trouble. Moreover, even if someone is bold enough to oppose him, his becomes a long fight. Such idealists may leave an impact on the society. But they do so at the cost of their own ruin.
- GeneralClass 12All
Why is Prem determined not to return to his village?
Prem is determined not to return to his village because of the violence there. In his village people burnt others’ houses and killed one another. These memories of his village made him burn with shame. So he di not want to go back there.
- GeneralClass 12All
5. Why do you think Prem wants to tell the story of the reptiles to the people of his village?
The people of Prem’s village quarreled with one another. The story of Pambupatti gives a message of peace and cooperation. It tells why it is necessary for different kinds to live together. So Prem wanted to tell the story of Pambupatti to the people of his village.
- GeneralClass 12All
Why did Makara dislike tortoises, snakes and lizards? Write a line about each.
Makara disliked ortoises because they were stupid and slow. They carried their houses on their back. He disliked snakes because they were very slimy and weird. He disliked lizards because of their strange habits. Moreover, some of them changed colour.
- GeneralClass 12All
What went wrong when the tortoises, snakes and lizards left the forest?
Many awful things happened. With no tortoises the jungle seemed to be rotting. Earlier, the tortoises used to eat the rotting fruit and the rotting animals in the river. When the snakes left the rats increased. They became the biggest nuisance. Similarly, when the lizards left, there was no fear to the insects. There were now millions of them growing bigger and nastier by the day. So the whole forest seemed to have gone crazy when the tortoises, snakes and lizards left it.
- GeneralClass 12All
When would you make a pact with the sun? When you are going on a picnic, or when you are playing a cricket match? Think of other occasions.
We would make a pact with the sun when we are playing a cricket match. We would also do the same on festive occasions and when we go on a picnic.