- 105

- 6

- Homework Statement
- A radar detects that a particle, located ##40 m## above the ground, moves towards it with velocity ##v_r=5 \frac{m}{s}##. The modulus of ##\vec v## is constant, and the modulus of the acceleration at that moment is ##a=10 \frac{m}{s}##. The radius vector that goes from the radar to the particle forms an angle of ##60°## with the ground. Find ##\ddot r##

- Homework Equations
- ##sin(x)=\frac{op}{hyp}##

I have a right triangle: one of the angles is ##60°## (that's ##\theta##), one of the sides is ##40 m## long, and the hypotenuse is equal to the radius. Now I can find an expression for ##r## and that expression is ##r=\frac{height}{sin \theta}##. If I differentiate it, I'll get ##\dot r## and if I differentiated it again I would get ##\ddot r##. Now, how can I differentiate that expression? because time doesn't appear in the expressions.