a little more than 34 days if this is the radial velocity A rocket launched from Earth will at first more or less accompany the Earth in its orbit around the Sun at an average velocity of 30 km/s (108,000 km/h). To simplify things, I assume that Earth and Venus are travelling on concentric circular orbits around the Sun in the same direction: - Earth at 29.78 km/s (107,200 km/h) at 149,598,023 km from the Sun, - Venus at 35,02 km/s at 108,208,000 km from the Sun. So, to get from the surroundings of the Earth to the surroundings of Venus, you will have to speed up your cross-radial (tangential) velocity from 30 to 35 km/s on the one hand, and you would have to travel from one orbit to the other by about 41,000,000 km in the radial direction to the Sun. Let's say that the 50,000 km/h in the question is the radial velocity, you will need: t = 41,000,000 / 50,000 = 820 hours which makes a little more than 34 days. Of course, this assumes that Venus will be in this precise location when you reach its orbit, which will only happen if you have used the appropriate launching window. Some of the actual flights: - the Soviet Venera 1: 97 days, - NASA's Mariner 2: 110 days, - ESA's Venus Express: 153 days. Further information: http://www.universetoday.com/36288/how-long-does-it-take-to-get-to-venus/ Also interesting: 'The Hohmann Transfer is an elliptical transfer orbit such that its periapse and apoapse just intersect the two circular orbits. The spacecraft makes two burns: one to transfer from the initial circular orbit to the elliptical transfer orbit, and one to transfer from the elliptical orbit to the final circular orbit. The Hohmann Transfer is constructed in such a way that both the spacecraft's initial burn and its final burn are aligned perfectly with its velocity vector at each of those points. Those points also coincide with the transfer orbit's periapse and apoapse. Since each burn is aligned with the spacecraft's velocity there is no wasted energy used in canceling out unwanted velocity.' Source: http://ccar.colorado.edu/asen5050/projects/projects_2001/parker/GEO.html Further information: https://solarsystem.nasa.gov/basics/bsf4-1.php http://www.braeunig.us/space/orbmech.htm#maneuver

1-23-2017 Your question exposes a very common misunderstanding about space travel. You don't go someplace by pointing your space ship at the destination and stepping on the gas. Everything in space is circling something else, and you move from one circle to another by orbital transfers, which might be a simple trip or it might take some clever math. The most common example of this mistaken understanding is the "space elevator". You don't get into orbit by riding an elevator to orbital altitude, you have to accelerate to orbital velocity. The space elevator concept omits the acceleration.