Akid on a playground swing makes 6 complete to-and-fro swings each 30 seconds.
the frequency of the swinging is
the period of the swinging is
(i don't really understand this can someone explain.)

100 grams of molten lead (600°c) is used to make musket balls. if the lead shot is allowed to cool to room temperature (21°c), what is the change in entropy (in j/k) of the lead? (for the specific heat of molten and solid lead use 1.29 j/g⋅°c; the latent heat of fusion and the melting point of lead are 2.45 × 104 j/kg and 327°c, respectively.)

What are the constituent metals of stainless steel?

What causes the appearance of lines in a emission spectrum