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1. Problem in understaning potential energy

Homework Statement If we lift a block with constant velocity, by applying a force mg upwards, is the work done zero? Homework Equations The Attempt at a Solution The work done must be zero as the resultant force is zero, what I don't understand is how does the block get potential energy if...
2. Direction of friction in circular motion

Homework Statement I can't understand why friction acts radially inwards when a body is rotating on a rough turntable. If the friction is removed, the body would move tangentially, hence it has slipping tendency tangential, not radially outwards, then shouldn't friction act tangentially...
3. Circular motion

Homework Statement A particle is moving parallel to x-axis in the positive direction with velocity v such that at all the instants the y -axis component of its position vector is constant and is equal to 'b'. Find angular velocity about origin. Homework Equations The Attempt at a Solution I...
4. Hybridisation doubt

There is an example given in my textbook showing the structure of BF3. In it, they have hybridised the orbitals of B to sp2, but not of F. It's written sp2-p overlapping. Why isn't flourine also hybridised, seeing it has 3 lone pairs and 1 bond pair, it could have sp3 hybridisation? Also, in...
5. Normal reaction doubt

Homework Statement My question is not a homework problem. I am having difficulty in understanding the concept oof contact forces. Homework Equations What I don't understand is that when two bodies A and B are in contact and left on a frictionless surface, they apply normal reactions on each...
6. Doubt in electromagnetic induction

Homework Statement suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil Homework Equations The Attempt at a Solution What I thought was that the current flows only in a closed circuit because it needs a potential difference...
7. How to make chemistry my forte

Hi everyone, I am a 10th grade student studying in India( would be in 11th in 2 months) I am not very good at chemistry. I have difficulty understanding the concepts. Although I don't have any doubts, I just don't feel confident. Also, my teacher is not very good. Whenever I would ask him...
8. Minimum and maximum resultant of three vectors.

Homework Statement In order to solve a question, I need to find the minimum and maximum resultant of three vectors, their magnitudes are given to me. Homework Equations Magnitude of vector A = 1 Magnitude of vector B = 3 Magnitude of vector A = 5 The Attempt at a Solution The maximum part was...
9. Where does the gene for green color come from?

I was studying evolution and speciation and an example was given in my textbook. It said that there is a species of red beetles and through variation a green beetle is formed and then is naturally selected as red beetles are easily seen by crows and green are not. My question is where does the...
10. Reaction of acids with salts

Hi I am new to the concept of neutralization. My teacher told me that acids do not react with neutral salts. I want to know why not. If both are dissolved in water and both completely dissociate, why can't the ions of acid and salt exchange and perform a double displacement reaction. Moreover I...
11. Vector problem -- Find the angle between vector A and vector B

Homework Statement Vector A + Vector B + Vector C = 0 A=B+C Homework Equations Find the angle between vector A and vector B The Attempt at a Solution I tried to solve this problem by resolving all the vectors and individually equating the value of vectors at each axes x, y and z to 0 but got...
12. How to get into Harvard, MIT or Princeton from India?

Hi everyone, I am a 10th grader studying in India. I want to know what it will take to get into universities like Harvard, MIT, etc. I have been getting 10 CGPA from class 6th to 9th,and i hope to score well in my boards. I am also a 5th grade pianist(Trinity) and I hope to complete upto 7...