Undergraduate science students face difficulties using mathematics in their physics courses. Choosing an institutional perspective, we consider that these students experience a permanent transition between mathematics in their mathematics courses and mathematics in their physics courses. We refer to the anthropological theory of the didactic and the notion of didactic contract to understand this transition. In France, the Maths4sciences digital resources have been designed to help students learn the mathematics used in physics. We investigate students' difficulties in the math-physics transition and the affordances and limitations of Maths4sciences resources to help them. We designed a physics exercise where students must recognize and solve a first-order linear differential equation. We interviewed three students who worked on this exercise and had access to a Maths4sciences tutorial sheet concerning such differential equations in a physics context. Through the analysis of these interviews, we observed that students faced different types of difficulties: recognizing mathematical types of tasks intervening in the technique for solving the physics exercise, performing types of tasks blending mathematics and physics, and making sense of physical notations, in particular. The Maths4sciences tutorial sheet only helped them with some of these difficulties. Beyond the cases studied, our work evidences the difficulties raised for students by different kinds of "recognition" types of tasks in physics and suggests directions for curriculum design and teaching mathematics for physics.