# Tagged Questions

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### How to get the derivative of a physical formula?

I've heard that if $U_{ind} \neq$ constant, you must use the following formula: $U_{ind} = N \times \dfrac{d \phi}{dt}$ I however don't know how to get the derivative of this formula? In math I ...
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### Finding the initial velocity using calculus

I throw a stone at 20 degree, when the stone falls to the ground, it reaches 100m further. Using CALCULUS methods, find the initial velocity of the stone.
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### The material derivative

Let $u:S(t) \to \mathbb{R}$ be a scalar field on a surface $S(t)$ parametrised by time. The material derivative is $$Du = u_t + v \cdot \nabla u$$ where $v$ is the velocity. I fail to understand the ...
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### Show the negative derivative [duplicate]

Possible Duplicate: Show the negative derivative of a function. A type of interaction between atoms in a molecule is called a Van der Waals interaction. This can be described by the ...
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A type of interaction between atoms in a molecule is called a Van der Waals interaction. This can be described by the potential energy function; $$U= ... 3answers 124 views ### Help with odd partial derivatives in velocity \bar v^2 = \dot x ^2+\dot y^2 I am doing a physics -course Tfy-0.2061. My teacher claims that this is velocity squared, \bar v^2 = \dot x ^2+\dot y^2. I cannot understand why it is not \bar v^2 = (\dot x +\dot y)^2. If ... 0answers 53 views ### When can I treat vectors as regular variables when differentiating? Given this Lagrangian where \dot{\vec r} = \left(\dot x, \dot y, \dot z\right)^T:$$ L = \frac m2 \left|\dot{\vec r}\right|^2 - q \left( \phi - \left\langle \dot{\vec r}, \vec A \right\rangle ...
Below I have a question that I tried to solve on a exam. I am curious as to the actual way to approach the question. What I did was set the equation equal to $0$ and get $t = -3$ then I plugged in $3$ ...