The outer electrons of many substances can be removed by friction
a. true
b. false

That's true.

That's EXACTLY what's happening when you scrape
your shoes on the carpet and then aappp your
brother from behind when he's not looking.

As you scrape your shoes on the carpet, either some electrons
get scraped off of the carpet atoms onto you, or else some
electrons get scraped off of the shoe atoms onto the carpet ...
I'm not sure right now.  But either way, YOU end up with a
net charge on your body, and when your pinky gets close
enough to the tip of your brother's ear, electrons jump across
to equalize the charge on both bodies.

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward