Change in direction of velocity

[ahmed emad]

If I'm driving a car and I have changed my dierction of motion without changing the speed, in this case how to calculate the acceleration of the car in a particular time? I'm not talking about circular motion.

 

[anorlunda]

Acceleration is change in velocity divided by elapsed time. How much elapsed time?

 

[ahmed emad]

I don't care about this , I care about that the change in velocity will be zero always , and in this case must be accelerarion.

 

[anorlunda]

I don't care about this , I care about that the change in velocity will be zero always , and in this case must be accelerarion.

Not true. Speed has no sign, but velocity does. If the initial velocity is +1 in some direction, then the same velocity in the other direction is -1, a change of 2.

 

[Dale]

I don't care about this

If you want to calculate acceleration then you have to care about the time. It is part of the definition.

 

[ahmed emad]

I know but it's an easy part , the hard part for me to calculate the change in velocity

 

[Dale]

$\Delta v=v_{final}-v_{initial}$

Don't forget that $v$ is a vector

 

[ahmed emad]

Ya,but but what if speed not changing only direction

 

[Dale]

It is still the same formula, but don't forget that v is a vector

 

[ahmed emad]

Okay , but the change in velocity will be zero and acceleration also will be zero , and that's wrong ,because if there is change in direction so it must be acceleration

 

[ahmed emad]

So should I make vectors addtion and use pythagorean theorem formula ?

 

[Dale]

Okay , but the change in velocity will be zero

No, it won't. Write it down and see. Remember v is a vector.

 

[ahmed emad]

Okay thank you very much