Sample Clues
A tokamak plasma nuclear reactor superheats isotopic nuclei of this element so that they fuse, releasing energy
hydrogen
At the Earth's surface, this force produces acceleration of about 32 feet per second per second
gravity
In 1589 he began experimenting in Pisa with falling objects using inclined planes to slow the rate of descent
Galileo
Graphite is a soft form of this element
carbon
A rocket's thrust may be measured in units named for this man whose laws of motion explain rocketry
Sir Isaac Newton