i need help in solving these GRASP problems

Module 7: Exemplary Level (2 marks) 3) An astronaut on the surface of a 6.50 X 1029 kg planet determines that an 80 cm pendulum requires 162 s to swing 50 cycles. What is the radius of the planet? Module 8: Developing Level (3 marks each) 4) Radio telescopes receive radiowaves from distant stars. If such a wave has a wavelength of 24 cm and travels at the speed of light (c = 3.00 x 108 m/s), what is the frequency? 5) The speed and wavelength of coastal water waves are 4.0 m/s and 6.0 m respectively. When the waves enter a shallower region, the speed decreases to 1.7 m/s. What is the wavelength in the shallower region?| Module 8: Proficient Level (2 marks) 6) A train whistle has a frequency of 900 Hz and is moving away from you at 32.0 m/s. Given that the speed of sound is 340 m/s, what is the apparent frequency you hear? Module 8: Exemplary Level (2 marks) 7) The first resonant length of a closed air column occurs when the length is 40.0 cm. What is the wavelength of the sound? What will the third resonant length be