A child 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?

The mass of the bike is 38.89 Kg.

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 dа ta:

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

Answer: the mass of the bike is 38.89 Kg.