A 0.22 kg pinecone falls 15.5 m to the ground, where it lands with a speed of 14 m/s.

a) With what speed would the pinecone have landed if there had been no air resistance?
(b) Did air resistance do positive work, negative work, or zero work on the pinecone?

Question

A 0.22 kg pinecone falls 15.5 m to the ground, where it lands with a speed of 14 m/s.

a) With what speed would the pinecone have landed if there had been no air resistance?
(b) Did air resistance do positive work, negative work, or zero work on the pinecone?

paxpolaris · Answer

for a)  mass is irrelevant ... use formula $$\Large v^2=u^2+2as$$where, $u= \text {initial velocity} = 0\ m/s$
       $a = -g = -9.8\ m/s^2$
      $s=-15.5\ m$

$$\Large v^2= 2\times9.8\times15.5$$


b) air resistance is in opposite direction of displacement ... so work done by  resistance is always negative

fellowroot · Answer