How much work is required to lift a 4kg object 3m high?

If a clock aboard a space ship traveling at 0.900 c of the speed of light relative to earth chimes once at the beginning of the hour and again when it reads one hour later, how much time would an observer on earth say elapsed between the two chimes?

Assume this car is driven off a cliff . how many arrows of force need to be drawn in the free body diagram? assume no air resistance -five -one -three -four

The frequency of the fundamental of the guitar string is 320 hz. at what speed v do waves move along that string?