Alarge stone of 20kg and small stone of 5kg are dropped simultaneously from certain height. which one will reach the ground first? why?

It is really hard for me right know

Acar travels in reverse. it covers 150 meters in 12 seconds what is the velocity of the car what is the speed of the car

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?