Need help answering these questions

1. A cannon is fired off of a 100 m high cliff at an angle of 25" with a speed of 30 m/'s. a) When will it hit the ground? b) How far from the base of the cliff will the cannon ball hit the ground? 2. A 12.0 kg box is released on a 30" incline and accelerates down the incline at 0.250 m/s'. Find the force of friction and the coefficient of friction. 3. A projectile is fired upward at an angle of 40" from the top of a 300 m cliff with a speed of 400 m's. What will be its speed when it strikes the ground? 4. A particle of mass in travelling with a speed v along the x-axis suddenly shoots out one quarter of its mass parallel to the y-axis with a speed of 3v. Give the velocity of the remainder of the particle (magnitude and direction). 5. A merry-go-round accelerates from rest to 4.0 rad/'s in 30 s. Assuming that the merry-go-round is a uniform disc of radius 7.0 m and mass 30 000 kg, calculated the net torque required to accelerate it. 6. A conservation of angular momentum or energy question. 7. Barium has a work function of 2.48 ev. What is the maximum kinetic energy of electrons if the metal is illuminated by light of wavelength 440 nm? What is their speed? 8. A clock on an alien ship orbiting the earth at 0.9c remains in orbit for a year, as measured by an observer on the Earth. Calculate the amount by which the orbiting clock and the earth clock will differ. Which clock is faster? Explain