Where would you expect light waves to move fastest?

If the textbook weighs 19.6 newtons on venus,what is the strength of gravity on venus?

What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source?

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?