What other achievements in space did the USSR accomplish?

First artificial earth satellite: Sputnik.  

First animals to successfully orbit the earth: Belka and Strelka.  

First on the moon: Luna 2 probe.

First man in space: Yuri Gagarin.  

First woman in space: Valentina Tereshkova.  

First spacewalk: Alexei Leonov.  

First remote-controlled rover on another celestial body: Lunokhod 1

c. mass = force / accellaration

step-by-step explanation: