Need help answering these questions

A 1. A rock is thrown from the top of a water tower with a speed of 15 m/s at an angle of 20" from the horizontal. If the rock lands on the ground 25 m from the base of the tower, how high is the tower? 2. A bar of soap slides down a 30 m wet frictionless incline at 40. Once it reaches the bottom of the incline the bar meets a dry horizontal surface with a coefficient of friction of 0.25. How far along the flat surface does the bar slide before coming to a stop? 3. A curling stone slides 30 m in 5 s when it has a collision with an identical stone at rest. After the collision, the first stone is deflected 30" at 2 m/s. Find the angle of deflection of the second stone? 4. A primitive way to launch a spaceship might be to use a sling shot. If a 10000 kg spaceship is to be launched using a 890 N/m spring, how far would the spring have to be compressed to launch the ship into space? The speed needed to escape Earth's gravity is 1 1 km's. 5. What is the frequency of 550 nm light? 6. What is the maximum order of diffraction possible for violet light (420 nm) illuminating a double slit with a separation of 8.4x10* m? 7. What wavelength is released if a photon drops from energy level n 4 to energy level n=1 in a hydrogen atom? In what part of the spectrum is this wavelength? 8. At what speed would an object have to move past you for their observed mass to double