# Recent content by borisleprof

1. ### Dimensionally correct equations

when you work with dimensions, use the fundamental units. mass : kilogram: [kg] length : meter : [m] time : second : [s] so speed ; [m]/[s] acceleration : [m]/[s]^2 force in newtons [N] = [kg][m]/[s]^2 work or energy is in joules [J] = [N][m] = [kg][m]^2 /[s]^2 When you have a formula, it...
2. ### Gravitation Constant

The gravitationnal constant is realy 6.67x10^-11 Nm^2/kg^2
3. ### Gravitation Constant

Hello everybody, gravitationnal acceleration is g = 9.8 m/s^2. It is when you analyse a situation let's say that an object is moving upward, you know that its weight is downward, so when you have a situation in which there are two opposite directions, you choose one that is positive (usually the...
4. ### Electric field with three charges

a test charge halfway between q2 and q3,call this point M, will experience a repulsion from q2, attraction from q3 with the same intensity. so the electric field at M will have a component along the line joining M and q3. But the same test charge at M will also experience a repulsion from q1...
5. ### Electric field with three charges

Hi flipstyle, you have an equilateral triangle, so if you trace a line which joint q3 and the midpoint between q1 q2, the lengh of this segment will be d√3/2. A test charge placed at halfway between q1 and q2 will be affected only by q3 since the influence of q1 and q2 cancel each other. So the...
6. ### Dalton's Law

When you heath water, the water pressure augment at the interface between water and air The boiling point of water vary with the pressure of the atmosphere. At sea level the boiling point is 100 ˚C where the air pressure is highest. At higher altitude the pressure of the atmosphere is getting...
7. ### Net force on charges found to be zero

I eltel, you must analyse two cases: A negative then B must be positive so that the net force be zero on p. A positive then B must be negative.... Then use Coulomb's law to complete your reasoning.
8. ### Derivative of inverse hyperbolic trigonometric functions

there is an error in the calculations of SatusX. The basic relation with hyperbolic function is cosh^2 x - sinh^2 x = 1. Now if y = sinh-1 x than x = sinh y dx/dy = coshy but cosh^2 y = 1+sinh^2y =1+x^2. so dy/dx =1/sqrt(1+x^2) where sqrt means square root. bye
9. ### How much total kinetic energy is needed in this case?

Hi eri3an, you must remember Einstein's equation : E = mc^2, where m is the mass of the particle when it is moving.
10. ### Problems with relativity

You have to remember the famous equation of Einstein: E = mc^2. Where m is the mass of the particle when it moves. the kinetic energie is the difference between the energy of the particle when it is movin and the rest energy (the energy that the particle has when it is at rest). You must know...
11. ### Qns on potential energy and forces

The potential energy is positive. So there is an attraction toward the origin. The force = - (dW/dx) = -2kx. So the force is directed from the point P to the point O, the origin. bye
12. ### Production of electric current

Suppose that the magnetic field is vertical upward. Suppose you have a round loop in a horizontal plane. Now rotate the loop along an axis wich is horizontal. What will happen to the flux of the magnetic field through the loop?
13. ### Does a current produce an electric field?

A current in a wire can be viewed as the two types of charges moving in opposite direction. Say in a horizontal wire, from left to right, negative charges moving to the left and positive charges moving to the right. So for a test test charge at rest outside the wire, the wire will be neutral...
14. ### Circuit that is both parallel and in series

I have juste made the calculations and I arrived at 0.98 watt ? 1 watt. So the result of sdekivit seems ok
15. ### Circuit that is both parallel and in series

I have juste made the calculations and I arrived at 0.98 watt ≈ 1 watt. So the result of sdekivit seems ok