Question about a change of velocity

[sidra]

velocity question

lets consider a body moving at 100m/sec in north direction...suddenly it turns in the east direction at the same speed and and continues moving in the east direction.....has the velocity changed...yes certainly...there is a change in direction...but the question is hw much....if u hv found the answer then....wt is the units of yr answer....if it is in m/sec...then the most important part "why"?

 

[ehsanelahimirza]

Re: velocity question

hi

yes the velocity has changed and its units are still same
why...?

it is bcz in velocity when we r talking about magnitude it is m/s

but when we talk about (actual amount) it is some m/s due north, due east or at some angle with a reference which is usually ignored in normal practice

 

[DrDolittle]

Re: velocity question

Yes velocity is said to be changing because of the change in direction. This is analogous to uniform circular motion in which the speed remains constant but velocity which is tangential to the position vector keeps changing the direction with a constant magnitude.

Regards
drdolittle

 

[Tinamuline]

Re: velocity question

Remember that velocity is a vector, we have to consider both of its magnitude and direction. By the time the object changes its direction of movement from north to east, then I can say the velocity of the object changes because back to basic, we have to consider both of the magnitude and direction of motion of the object.

 

[sidra]

Re: velocity question

well guys...a good responce from u.....but i want to know the exact value of change in velocity.....i know that the velocity has changed...but hw will u calculate it in this problem.....and will u express the change in m/sec in this specific problem....

 

[shivamrules]

Re: velocity question

well the velocity changes by x*2^.5...if it was moving with x initially

 

[Kral]

Re: velocity question

sidra,
The North component of velocity has changed by -100m/s
The East Component of velocity has changed by +100m/s
The Speed has not changed.
You must consider all three components of velocity. In this case, we are ignoring the vertical component.
Regards,
Kral

 

[shivamrules]

Re: velocity question

yes
u can do this in the vector form
initially it was 100i
finally it was 100j
so change in velocity isthe magnitude of 100i-100j which is 100*2^.5 that is arnd 141.4
change in speed is ofcourse 0
byie

 

[sidra]

Re: velocity question

wt i hv understood is that there is only change in direction which can be expressed in vector notation...and the change in vector notation is given by..... 100(i-j)....is it right...

 

[yousefsam]

Re: velocity question

Dear,
the velocity if its change then the angle of its motion will chage from this relation :
v = v(at the dirction of north) + v(at the direction of east)
If you assume the direction of motion as a unit vector you can take the dirction of north as (jΛ) vector and the direction of east as (iΛ) vector .
then you can solve the question as very easy by Using vector method and find the angle of motion for the relation v(final) = tanΛ-1(v(jΛ)/v(iΛ)) .
the answer of your question the angle of motion depends on the velocity at north and east directions if its change the velocity will chage ,
and the Unit of final velocity is the same unit of velocit (m/sec) .
And if we change the velocity in magnitude the direction of it will change .
Yousef Omran