Prove in case of projectile d^2 (v^2 ) / dt^2 = 2g^2

[Safi Majid]

Homework Statement

for a projectile show that d^2 (v^2) / dt^2 = 2g^2

2. The attempt at a solution
=d/dt (d(v^2)/dt)
=d/dt (2v)

 

[Orodruin]

Your attempt is using a very strange notation. Please write out the details using standard notation and explain what you are doing in each step.

 

[ehild]

Homework Statement

for a projectile show that d^2 (v^2) / dt^2 = 2g^2

2. The attempt at a solution
=d/dt (d(v^2)/dt)
=d/dt (2v)

Welcome to PF!
The velocity v depends on t. You need to apply the Chain Rule to get the time derivative of v².

 

[Safi Majid]

Your attempt is using a very strange notation. Please write out the details using standard notation and explain what you are doing in each step.

i have used second derivative on it

 

[Safi Majid]

In standard notation it is
d²(v²)/dt²=2g²

 

[HallsofIvy]

That was not what was being questioned. The derivative of $v^2$, with respect to t, is NOT "2v". It is $2v\frac{dv}{dt}$.