Question

A frog is sitting on a lily pad when it sees a delicious fly. He darts out his tongue at a speed of 3.90 m/s to catch the fly. The tongue has a mass of 0.410 g, and the rest of the frog plus the lily pad have a mass of 12.5 g. What is the recoil speed of the frog and the lily pad? Ignore drag forces on the pad due to the water.

Answer 1

Recoil speed of the frog and the lily pad, v₂ = 0.124 m/s

Step-by-step explanation:

According to the law of conservation of linear momentum, in a closed system of colliding bodies, the momentum before collision is equal to the momentum after collision.

Momentum before collision = m₁v₁

momentum after collision = (m₁ + m₂)v₂

where m₁ = mass of the tongue; v₁ = velocity of the tongue; m₂ = mass of th frog and lily pad; v₂ = velocity of the frog and lily pad

m₁v₁ = (m₁ + m₂)v₂

v₂ = (m₁v₁)/(m₁ + m₂)

m₁ = 0.41 0 g = 0.00041 kg; v₁ = 3.90 m/s/; m₂ = 12.5 g = 0.0125 kg; v₂ = ?

v₂ = (0.00041 kg * 3.90 m/s)/(0.000410 + 0.0125 kg)

v₂ = 0.124 m/s