# Search results

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...