: You have an unknown tuning fork, it hits its first resonance at 31cm. What is its frequency?

9.7 Hz

Explanation:

Given that

c = γν

where

c = speed of light = 3*10^8 m/sec

λ = wavelength of the sound = 31 cm = 0.31 m

ν = frequency

Applying the formula directly, we have something in the nature of

3*10^8 m/sec = 0.31 m * ν

Making v subject of formula, we have

ν = 3*10^8 m/sec / 0.31 m

ν = 9.7 sec^-1

v = 9.7 Hz

This means that it's frequency has been calculated to be 9.7 Hz

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.