Achild is riding a bike at a speed of 0.6m/s with a total kinetic energy of 12.4j. if the mass of the child is 30kg, what is the mass of the bike?

Ek=kinetic energy  (J)
m=mass of object (Kg)
v=speed of object  (m/s)

We have the following formula:

Ek=(1/2)mv²   ⇒ m=2(Ek)/v²

In this case:
m= mass of the child + mass of the bike
m=30 kg + m₁       (m₁=mass of the bike).

We would have to modify our formula like this:

m=2(Ek)/v²
m=30 kg + m₁

30 kg +m₁=2(Ek)/v²
m₁=2(Ek)/v²-30 kg

We have the following data:

v=0.6 m/s
Ek=12.4J
m=30 Kg + m₁

Therefore:

m₁=2(Ek)/v²  - 30 kg
m₁=2(12.4 J)/(0.6 m/s)²  - 30 kg
m₁=24.8 J/(0.36 m²/s²)  -30 kg
m₁=68.89 Kg - 30 kg
m₁=38.89 Kg

the mass of the bike is 38.89 Kg. 

The mass of the bike is 38.89 Kg. 

What is the things about?

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.