v(r)= k(a-r)r^2 where k is a constant

evaluate v at a.

This is what I got when I solved but it is not correct.

v(a)=k(a-a)a^2
v(a)=ka^2

v(a)=k(a-a)a^2 correct

v(a)=k(0)a^2
v(a)= 0 , zero times anything else is zero

oh i see

To evaluate v(r) at a specific value of r (in this case, at a), you need to substitute the value of r into the equation for v(r) and simplify.

Given the equation: v(r) = k(a - r)r^2

To evaluate v(a), substitute a for r in the equation:

v(a) = k(a - a)a^2

Since (a - a) equals 0, the equation simplifies to:

v(a) = k(0)a^2

Any term multiplied by 0 is zero, so the final result is:

v(a) = 0

So, the correct evaluation of v(a) is zero, not ka^2. It seems there may have been a mistake in your previous calculation.