The angle of friction of this material is 30 degrees.

My apartment is a five-story building.

He was standing on the seashore, staring at the distant horizon.

His actions are nothing short of vulgar.

He hit a jackpot at the pachinko.

The number of nuclear-armed countries is increasing worldwide.

He picked up a shell on the beach.

Cold fusion is a part of physics and is a phenomenon that is not yet fully understood.

Research on cold fusion is still controversial.

The development of fusion reactors could potentially be the key to solving future energy problems.