[Math] Quadratic formula with negative square root

physicsquadratics

I encountered this while doing a very basic physics question (so I hope you don't mind if I post it, the problem lies within my math anyways): A stunt vehicle leaves an inclined slope of 28 degrees with a speed of 35 m/s at a height of 52 m above ground level. Air resistance is negligible.

What is the vehicle's time of flight?

$D = \frac 1 2 at^2+V$ (initial vertical velocity) $t$

is the formula for displacement out of which we can get a quadratic equation to solve for $t$ (time)

$0 = 5\,t^2+\sin(28)\,35\,t + 52$

Now when I plug that into the quadratic formula it gives me a negative under the square root and we are definitely not working with complex numbers. How do I solve for $t$?

Thanks,
John.

Best Answer

I think you need $-5$ where you have $5$.

(And "negative square root" isn't exactly the right term. It would be a square root of a negative number. What's negative is not the square root, but something else.)

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