# Sequence of Learning Physics

In what sequence should these chapters be prepared for my exams:- units and dimensions,kinematics,laws of motion,work power and energy,motion of system of particles and rigid body dynamics,gravitation. Apoorv Katoch asked Answer: It is better to follow...

# Homework from vectors

A man walks 10 km towards west and then 12 km (60 degree_ direction of North-East. find the resultant vectors, magnitude and direction. A man walks 10 km towards west and then 15 km towards south. Find the resultant vectors, magnitude and direction. Ju...

# Can light do some mechanical work?

“We know that sound can cause some mechanical work(eg:when we keep our hand in front of a large speaker,we feel something hitting the back of our hand), but why this doesn’t happen with light??” -Manishankar asks. Link to this post! ...

# Preparing for IIT JEE Physics

Yudhvir asks: “Hello Sir!!! I m in 11th!! I want to do less work & more benefit!! I don’t like to study at all!!…but i have decided to do only DC Pandey!! is it enough for IIT preparation???”   Answer: No pain, no gain! Whatever be the book you follow, understanding the basic concepts is all [...]

# Misconception on Work and energy conservation

It is said that when work is done energy is lost. But when a man runs in a circular path and reaches the starting point, then the work done is zero but energy is lost. (Divyam asked) Answer: The work done here is not zero, work is done and energy is spent to overcome friction. [...]

# Is law of conservation of energy violated here?

“When a body is moving with uniform speed on a rough surface under the application of a constant external force and an equal and opposite frictional force, the work done by both the forces should be equal. as a result, the net work done by both the forces should be zero. however, we find that [...]

# Dimensional Analysis – A solved example

Deduce the dimensional formula for workdone,pressure and density. [posted by boineelo ] Answer: workdone We know that workdone = force x distance Therefore [work done] =  [force] [distance] but force = ma [force]=[m][a] [a]=[velocity]/[t] [velocity]=[displacement]/[t] So, putting all these together [work done]=[m][distance][distance]/[time][time] [work done]=ML2T-2 Similarly, you can work out the dimensional formula for pressure and density as [pressure]=[force]/[area]=ML-1T-2 [...]