Answer:
the answer is the red super giants
According to given condition there is no height(m) given from roof of building to the ground, there height given 18 m at a point above the ground. So, h=18m , mass=3kg , g=9.8m/s2 P.E=mgh P.E=(3)(9.8)(18) P.E=529J
Iron nails are attracted to the magnet
Question: How fast was the arrow moving before it joined the block?
Answer:
The arrow was moving at 15.9 m/s.
Explanation:
The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:
where is the mass of the arrow, is the mass of the block, of the change in height of the block after the collision, and is the velocity of the arrow before it hit the block.
Solving for the velocity , we get:
and we put in the numerical values
,
and simplify to get:
The arrow was moving at 15.9 m/s