Does the phrase diretion of zero vectro have physical significance?Discuss in terms of velocity, force etc.

Show that a force that does no work must be a velocity dependent force.

A physical quantity is a phyical property of a phenomenon , body, or substance , that can be quantified by measurement. The magnitude of the components of a vector are to be considered dimensionally distinct. For example , rather than an undifferentiated length unit L, we may represent length in the x direction as L_(x) , and so forth. This requirement status ultimately from the requirement that each component of a physically meaningful equation (scaler or vector) must be dimensionally consistent . As as example , suppose we wish to calculate the drift S of a swimmer crossing a river flowing with velocity V_(x) and of widht D and he is swimming in direction perpendicular to the river flow with velocity V_(y) relation to river, assuming no use of directed lengths, the quantities of interest are then V_(x),V_(y) both dimensioned as (L)/(T) , S the drift and D width of river both having dimension L. with these four quantities, we may conclude tha the equation for the drift S may be written : S prop V_(x)^(a)V_(y)^(b)D^(c) Or dimensionally L=((L)/(T))^(a+b)xx(L)^(c) from which we may deduce that a+b+c=1 and a+b=0, which leaves one of these exponents undetermined. If, however, we use directed length dimensions, then V_(x) will be dimensioned as (L_(x))/(T), V_(y) as (L_(y))/(T) , S as L_(x)" and " D as L_(y) . The dimensional equation becomes : L_(x)=((L_(x))/(T))^(a) ((L_(y))/(T))^(b)(L_(y))^(c) and we may solve completely as a=1,b=-1 and c=1. The increase in deductive power gained by the use of directed length dimensions is apparent. Which of the following is not a physical quantity

Answer the following : (i) A vector has magnitude & direction. Does it have a fixed location in space? Can it vary with time. (ii) Will two equal vectors vec(a) & vec(b) at different locations in space necessarily have identical physical effects? (iii) Can three non zero vectors, not in one plane, give a zero resulatnt? Can four vectors do ? (iv) Can a vector have zero magnitude if one of its components is not zero?

Assertion: Pseudo force is an imaginary force which is recongnised only by a non-inertial observer to explain the physical situation according to newton's laws. Reason: Pseudo force has no physical origin, that is it is not caused by one of the basic interactions in nature. It does not exist in the action-reaction pair.

A very has magnitude and direction . Does it have a location in space ? Can it very with time ? Will two equal vectors a and b at different locations in space necessarily have identical physical effects ? Give examples in support of your answer .

A body of mass 1 kg moving with velocity 1 m//s makes an elastic one dimesional collision with an identical stationary body. They are in contact for brief time 1 sec . Their force of interaction increases form zero to F_(0) linearly in time 0.5s and decreases linearly to zero in further time 0.5 sec as shown in figure. Find the magnitude of force F_(0) in newton.

(a) Magnetic field lines show the direction (at every point) along which a small magnetised needle aligns at the point). Do the magnetic field lines also represent the lines of force on a moving charged particle at every point? (b) Magnetic field lines can be entirely confined within the core of a toroid, but not within a straight solenoid. Why? (c) If magnetic monopoles existed, how would the Gauss's law of magnetism be modified? (d) Does a bar magnet exert a torque on itsell due to its own field? Does one element of a current-carrying wire exert a force on another element of the same wtre? (e) Magnetic field arises due to charges in motion. Can a system have magnetic moments even though its net charge is zero?

When does the average velocity become zero?

If Pressure, mass and velocity are fundamental physical quantities, the dimension of force (F) will be