Different masses are hung on a spring scale calibrated in newtons. the force exerted by gravity on 1.0 kg is shown in the image below in newtons. what would be the force exerted by gravity on 9.0 kg?
a. 9.0n
b.9.8n
c. 81n
d.88 n

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

The geological theory that states that pieces of earth's lithosphere are in constant slow motion is the theory of plate tectonics.