Is it true or false that all electromagnetic waves travel at the same speed in a vacuum?

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?

Marvin records scientific data about lake superior. for which property has marvin forgotten to use an si unit of measurement? shore length high temperature low temperature annual precipitation

Which of the following is not a means to accelerating? question 4 options: a)increase speed b)remain still c)decrease speed d)change direction